Alright now that things have calmed down a bit, time for my thoughts of these leaks. Of course this is all ASSUMING the OP is even accurate so I am taking this with a grain of salt.
*Fiscal 2019 year release date makes sense if it hasn't been unveiled already. Capcom is doing a less than a year from unveil to release which means that E3 2018 unveil would put it at early 2019 release. Seems to check out. However, if it gets announced this year that means even late 2018 is on the table. Either way it falls neatly into late fiscal 2019 year.
*The game being called DMCV instead of DMC5 is very peculiar and has implications. First thing that comes to mind is that it might be focused on Vergil and his return. It's a no brainer marketing gimmick. Other than that it could just be as stated like MGSV where it's just cooler to put down a V instead of a 5.
*PS exclusivity is interesting but not that surprising. I hope it's not more exclusive than SFV because a big chunk of the hardcores that play DMC even to this day are PC players. Would be a huge shaft to the those players. I would want DMC to be on as many consoles as possible but just like in Bayonetta's case, this might be a "either we get DMC exclusive or no DMC at all." Just have to accept the console politics in that case.
*The trailer bit is not a lot of info to go by but returning to city landscape is a bit disappointing. If this is in fact going to be the "end of son of Sparda" storyline then I want to see crazier landscapes and hellish environments. Hopefully only the initial stages are shown in the trailer and the crazier stuff is saved for later. I don't want Fortuna 2.0 again. And of course I hope the initial trailer has game play in it too because it would not be cool to wait this long and not even see actual game play which is the most important part of these games.
*Ambitious and broader appeal... this could go either way. At this point a lot of people would not have been taken kindly to DMC5 if it was just DMC4.5. People want a BIG jump if we had to wait 10 years for it. At that same time... ambitious means risker/more expensive game and that means they have to make sure as many people play this game as possible. I just hope by broader appeal they mean stuff like visuals and quality of life improvements, maybe some streamlining here and there but not at the risk of lowering the skill ceiling of the game that they have known for. I am all for lowering the skill floor in any way they can... the sooner people can go from pressing buttons to styling on fools the better, that's one of the things that DmC did right (but it did it at expense of some skill ceiling).
*Longer cutscene time makes sense if this is going to cover as many characters and plot points as is being implied. DMC3 was under 2 hours while DMC4 was almost 2 and a half hour. Despite having 1 more hour of story, DMC3 still managed to tell a more coherent and focused story than DMC4. So number of cutscenes doesn't matter to me as much as quality of them. I would assume that we are going to have a game that is close to 3 hours in cutcenes. If they use the cutscenes well then it will be fine otherwise it could easily end up as a bloated mess.
*Itsuno's old team, Yuji and the 3 main actors reprising their roles is very comforting. This also confirms that those characters are in some capacity. Major implications about story and characters there, more on that later.
*No word on Lady yet and that's probably because Lady has gone through multiple actresses. Even if she was in, most people wouldn't even know based on the cast list. They could easily have hired a new actress for her.
*Two things pop out to me: Trish prominent role and new very powerful playable character. Does this imply that Sparda is going to be back and be playable? That would be a massive development but not that surprising if this is in fact the end of son of Sparda storyline. The playable character could just be referring to Vergil or a new character but for reason it sounded like Sparda to me. Man how bad ass would be to have some flashback sequences of Sparda in this game.
*Onyay is probably is just making the main title song of the game, I doubt she is going to be super involved with every aspect of the game's soundtrack.
*The story stuff is.... ambitious to put it simply. It seems like they are trying to do too much at the same time... treating it like this is going to be the last DMC ever. They are trying to resolve Dante/Trish/Sparda stuff, Mundus, Nero + Vergil all in one game. I have seen this type of stuff attempted in movies and it rarely works as some aspects become underdeveloped. Maybe they can make it work with a longer cutscene time but I have my reservations. As far as the comment about Prince of Darkness goes... come on now, unless this is misdirection this is most definitely referring to Mundus. Which is a bummer because I would've liked to see a stronger villain than him but oh well.
Game Play Systems
Oh man where do I even begin. Honestly when I expected a DMCV leak I was not expecting we would get juicy game play stuff too but here we are.
*Lock on and 60FPS is a no brainer. I just hope that they allow for a toggle feature on lock on like in DmC DE.
*Level design more open and better traversal... sure I guess. DMC level design was PS1 level of archaic stuff, let's get out of early RE constraints already. DMC isn't some scrawny human being that has trouble jumping over waist high crates... the level design should better reflect this. Also the word "smooth" gets thrown out a lot... interesting.
*It's also similar to Bayonetta which means more set piece driven as stated. That probably means a lot of fancy sky boxes and stuff just happening. As long as there aren't QTEs and the sequences aren't too intrusive I am ok with that especially if it gets the casuals in.
*No stamina bar has to be some inside joke that I am missing. I don't know why that was specified here, seems like a meme. Pretty sure I would not even consider buying a DMC game if I got word that it had stamina bars (I would probably still buy it but I would complain a lot!).
*More enemy count is not really a good thing for these type of games. They are more about close encounters with a few folks. This also means that instead of expanding the AI like they should be doing, they are just going to keep them dumb and just throw more of them at you like LDK mode. I really hope for challenging enemies in DMC in general.
*No PvP multiplayer is good. I don't want the team to be wasting resources that would take a whole combat rework to get right, it's really not worth it IMO. But hopefully some co-op is in the game though.
*Dodge system reworked - THANK GOD! I know a lot of hardcore DMC fans are going to come in and be like "BUT WHY REWORK THE DODGE SYSTEM? IT'S FINE AS IT IS!" This is a big topic that deserves its own time in the light but DMC's dodging system is archaic as hell and not really helpful for new players. The way you ultimately dodge in this game is counter to how you first learn to dodge. Any change that allows players to naturally progress their skill is a good one IMO. As far as hardcore players go... think long and hard of the last time you saw a high level DMC combo video and they were doing regular old ground roll dodges. Even in high level play it's not common because they are not stylish and they don't allow you to do what you really want to be doing in the game.
*Dynamic camera is interesting I just hope this doesn't mean it's like GoW where it's always fixed. I hope we have a fully rotatable camera like in DmC and that the camera adjusts based on player proximity to enemies. I also hope it's not intrusive for the combat.
*Animations, physics and general tech improved over previous DMC games is probably expected. You don't want the game to look like it's basically DMC4.5.
*Mission/ranking system like previous games means it most definitely is not open world. I have to wonder what the DD inspirations are though because so far it seems very much like an old school DMC game rather than an ARPG.
*Dynamic environment is alright I just hope it doesn't result in random frame drops. Probably is related to the set pieces in the environments.
*Bosses being ramped up... good. I think this also means that there might be multiple phases to bosses now. DMC had these but it was more subtle. Given how a boss apparently moves between different areas tells me multiple phases are going to be more pronounced. I just hope we don't have a bunch of Savior tier fights because that is just not OK.
*Style system being back and being changed... expected. You can't expect someone new to the game to give them 5 on the fly styles to use from the gate and expect them to get anything out of it. People who have been playing DMC4 for 10 years will never realize this and will automatically wince at any word that the system is being "streamline." As long as number of options isn't being limited, this is ultimately a very good thing. I have already proposed some layouts where they can do this so I hope that Capcom uses something similar to it.
*Stuff about enemies reacting/more susceptible to Styles.... no idea how this will work in practice. Especially considering that you are changing styles rapidly, I don't know how the enemy AI will react to that. I think it just might be pretty basic stuff like some enemies go more airborne if you are using a lot of Swordmaster attacks and you need to use Trickster to chase them around.
No word on systems for other characters like Nero. No information on engine, I would assume Capcom isn't going crazy and will probably either use UE4 or MT Framework. No leak on control scheme which is a big deal too. Still a lot of stuff missing already but of course I will not complain, this is a lot of stuff to talk about in time.