White Owls and Experience Inc are both on the smaller side and have some history working with Xbox. Mistwalker also has a history with Xbox and have been growing in to a full development studio recently with their next game going to Apple Arcade. White Owls honestly seems like the most likely out of this entire list, as they're the only ones that have successfully crowd funded a game, which is something every other acquisition except Playground games has done at least once. It proves they're fans will show up.
Tomonobu Itagaki and Yukio Futatsugi have worked with Microsoft some in the past as well and both head up independent studios, so Valhalla Games or Grounding Inc could happen. Valhalla Games also has offices in Canada, so that'd make them less isolated. Cyber Connect 2 also has an office in Canada and they've been pretty keen on gaining their creative freedom recently, but they're also pretty big.
Tri-Ace and Tri-Crescendo have both worked with Xbox some in the past and have a pretty serious pedigree, they'd be like the Obsidian and InXile of Japan if they were acquired together in my opinion. Though Tri-Ace isn't actually independent, they're owned by a mobile software company. They're not a console games publisher and it doesn't seem that Tri-Ace has been all that successful of an investment for them in the last 5 years, so it's not impossible they'd sell.
On that same line there's From, but From is doing pretty well lately so I doubt Kodakawa would sell them. People also keep bringing up Hajime Tabatas new studio, JP Games, but I'm not really sure why we think they're likely.
Major Longshots would be Kojima Productions and Level-5. Level-5 would be absolutely massive, but I could see them being Xbox's only Japanese addition, since they're multiple studios with multiple IPs and genres. Doesn't really fit the current MO, but Japan might be different. Kojima I just like bringing up because I worship chaos.
And then there's Kemco. They've been releasing a lot of games on Xbox, but they're not really ambitious or super beloved. Might be low hanging fruit, and could maybe grow to be something awesome, but I doubt it's worth it.
I think I covered pretty much everyone, but I'm also positive I missed a few. It's also possible they could acquire a studio they've never worked with completely out of left field, but at that point I'm just naming independent studios.
