I like the wishlists and seeing everyone's ideas. Here are mine.
343 - Halo: Infinite will theoretically be the end of the current Halo trilogy. For their next project, I would like to see 343 do something that mixes it up, maybe even just as a one-off. Switching up the genre would be really interesting, even if it was a smaller project with a faster development cycle or with a limited team and not the whole studio. I personally think the idea of a shorter narrative experience based on one of the more interesting Halo novels or a "Rogue Squadron" equivalent with a Crimson Skies spiritual successor in the Halo universe with a story campaign and a few online multiplayer modes are great ideas.
Compulsion - I think Compulsion's next project should be a 2D-platformer to kind of get their feet wet under the XGS banner. I think that both Ori and Cuphead's futures are a bit up in the air, and 2D platformers have huge followings. I think something a bit darker with great environmental storytelling would be a good fit from Compulsion. Something like Limbo with a bit more focus on running and jumping could be a really good addition to the catalog.
inXile - This one is easy for me. I'd love for inXile to have two teams making RPGs with unique settings and gameplay. I think that the most likely scenario is one team works on AAA first-person RPGs and one team works on AA CRPGs. I think the balance of setting is really difficult between Playground, Obsidian, and inXile. I would like to see a nice mix of genres. Personally, I think a "supernatural" RPG set in a modern time would be really interesting. Sort of like Quantum Break, but with different powers and abilities. It'd also be a nice balance with Wasteland, Fable, The Outer Worlds, and Pillars of Eternity.
Obsidian - I personally think that the path for Obsidian is obvious. If Outer Worlds is great, I would like Microsoft to buy the publishing rights and continue the series. I'd also like to see Pillars of Eternity come back for at least one more game, although I wouldn't be disappointed if Obsidian moved onto a new IP.
The Coalition - Not unlike 343, I'd like to see The Coalition take a bit of a Gears breather after Gears 5. I'd like to see them work on a smaller, quicker project, either inside the Gears Universe or out. Others here have speculated that The Coalition could make a horror game based in the Gears Universe and I think that's a great idea. Something like The Evil Within with ties to the Gears universe would certainly get me excited. A bigger wish I have for The Coalition is that they get a second full team and work on another project concurrently with Gears. I think Rod is a great studio head and everything about The Coalition screams efficiency, so I'd be excited to see what they could do with more muscle.
The Initiative - I don't think The Initiative is making Perfect Dark, but it's a wishlist right. If I was picking which project they were doing, I'd do a science-fiction open-world Perfect Dark reboot where you play as Joanna Dark, who is a detective facing a new threat in the city that she serves. The gameplay could be similar to GTA with a city filled with things to do and new missions, but I would emphasize how vertical the city is and include flying cars. The lower levels of the city could be seedier and the upper parts could be quite posh. It could all feel very much like Minority Report.
Turn 10 Studios/Playground Games (Racing Team) - I think that Forza should mix up their formula a bit by ditching the Forza Motorsport and Forza Horizon names (after one entry each to solidify the brand on next-gen). It would be really cool if every year, the theme of Forza was different. Maybe Playground could work on Forza Street one year, while Turn 10 made Forza Rally the next year. I just think they need to mix things up a bit and it'd be a good start.
Undead Labs - I love State of Decay 2, despite all of its limitations. I'd love to see them really get all those frustrating limitations ironed out in the next State of Decay. I'd also love a bit of a new setting for State of Decay 3. I'd love a nice mix of rural areas and a city that feels like a city and not just a small collection of buildings.
Xbox Global Publishing - I would love for Xbox Global Publishing to change their targets a bit. If you're going to make a AAA game, make sure it's worthwhile by investing in a quality studio and putting them in a position to succeed. I feel like their track record on the larger titles this generation has been a bit spotty. If they're not going to invest in quality AAA games, I'd actually rather see them increase the number of AA and A games they partner with. These projects are a smaller risk, but can turn into amazing games if you partner with passionate creators with unique ideas.
Mojang - I love the idea of Minecraft: Dungeons. I hope it gets a ton of support and still feels uniquely Minecraft. If it's well-received, I hope they have a really cool support plan to load it with new content as time goes on.
Ninja Theory - My wish for Ninja Theory is three teams, two teams that make narrative-driven singleplayer experiences like Hellblade and a third team that makes more traditional video games like Enslaved. This would give Ninja Theory a game every 12-18 months and would be great additions to the catalog. For the narrative experiences, I just want Ninja Theory to get weird with it, like they did with Hellblade. I thought that was a totally fun and unique experience. I personally would want a game in the vein of Hellblade where you play as a cult-leader and hear a voice in you head that your character mistakenly believes is god. For the more traditional game, I'd like to see an action-adventure game in whatever unique setting that Ninja Theory dreams up.
Playground Games (Fable Team) - I would like to see the team reboot Fable entirely (throwing out everything) and just make the game they want to make. I think part of the reason that it's been reported that it is and isn't Fable or that plans have changed is because Playground isn't doing something that would fit our expectations of Fable. I think they should keep the Fable name, but let Playground do whatever they want. The thing I personally would like to see most is a unique sense of scale. Giants that are giant, castles that seemingly pierce the sky, but still smaller details like bugs and rich terrain.
Rare - Like Ninja Theory, I would like to see Rare go forward with multiple teams and a mix of smaller and larger experiences. I actually think Rare has done a great job managing Sea of Thieves as a GaaS, but I don't find the gameplay loop to be particularly satisfying. I would like for their next large project to be a new GaaS, but something entirely original. They tweeted some of the other ideas they had when they were developing Sea of Thieves and I think the alternatives were really interesting. I'd love to see one of them put into practice. Developing games like that can take a long time. In the meantime, I'd like to see Rare work on a smaller new project, similar to Banjo or Kameo, that will appeal to a different audience, but fill an important need for the catalog.