Why do people keep saying Ishin needs to be remastered? IT DOES NOT! Its a PS4 game. It runs at 60FPS/1080p like every other old engine game on the PS4. It just needs to be translated. That's it. Maybe tweak some friendship stuff while your at it but remaster it? Why?
The only PS4 Yakuza game that needs remastering is 6, and that's just to make the game "complete" - as in - put the shit not in the game I want back into the game - all of Kamurocho, weapons, some more mini games maybe. Ishin is fine as is, it'd be the biggest waste of resources to remaster that game.
Anyway, 2 doesn't need remastering, that was already done on the PS3/Wii U (the HD collection with 1&2), then it was remade into Kiwami 2.
Kenzan will probably be remade, not remastered going by what RGGS said recently. I personally just want it remastered though.
The PSP games would probably be remade not remastered - they use the old static camera system for exploration, and could benefit from a full 3D world - the second game especially uses some really low res static images for some areas, it'd be a huge benefit having them change the way it looks, especially as certain smaller areas are very hard to see/access unless you know the entire map like the back of your hand. Also, it'd be really handy for avoiding fights, as in premium adventure mode the AI level shoots way up above your own, so avoiding fights until you level up a bit is advised. Combat should be left largely unchanged though, as its bloody great, maybe see if they can make it work a bit better when fighting more than one foe but that's really it.
And then you have Dead Souls (which I notice no one mention btw ;) ). Which despite people's opinion on it, is actually the game MOST needing a remaster. Seriously, just slap that in 60FPS and already the game is improved because its always had the most FPS problems in the series. Now if they could also improve or just go all out and redo the aiming/shooting it'd be even better. I wouldn't want a dragon engine remake, just a remaster though so I can keep that 60FPS.