We can speculate all we want about the closure of Tango, but until someone comes out and publicly says otherwise (which they probably won't because why would the?), the only explanation that holds enough water is that they weren't making enough money.
The idea that it's difficult to manage a Japanese studio as an American company makes sense, until you mention that that American company is one of the largest in the world and has had Japanese subsidiaries since the 80's and is still actively hiring people in Japan. Not to mention that the current era of Xbox is famous for "Hands off" management, sometimes to their own detriment.
I've seen some people speculate that they needed to shut down
someone and they chose Tango because Mikami left and the studio didn't have the same prestige without him. Which starts to fall about when you consider that Mikami hasn't directed a game since the first Evil Within, and also that they shut down Arkane Austin, where Harvey Smith was still actively directing games. Tameem Antoniades having recently left Ninja Theory doesn't necessarily invalidate this theory, but it does add to it in not great ways.
Ultimately all of the other things
could have contributed to the choice, could have contributed to picking Tango and Arkane over another studio, but either way, this wasn't a decision that was a long time coming because of some flaws at the studios.
Xbox became an 80 billion dollar business, and now they're refocusing resources, so Tango, Arkane, Roundhouse and Alphadog became line items. Maybe there was a list of bottom earners and Booty or Spencer got to pick from the list, and I don't think any other pairing on that list would make anyone feel better. It's weird because I always felt that could have been the same situation when they closed Lionhead. Spencer came in and had to close some studios, and he chose Lionhead. And I have defended that decision to some extent in the past. I wasn't happy with it, but the state of Xbox at the time, it felt inevitable. Xbox isn't exactly flourishing right now either, but it's not the same situation now as it was in 2017. Even in a few years with hindsight I'm sure I'll look back at this and still think it was a bonehead move.
I honestly wouldn't be that surprised if in a few years they're making some acquisitions in Japan or Korea though, when Xbox has settled into the shape they wanna be beside Activision. Maybe this is an every 7 or so years thing for Xbox now. Close some studios, then buy some new ones. Wasn't it around 2010 that they closed Ensamble, FASA, Aces and Digital Anvil?
Maybe they'll try to win back trust by announcing their dedicated handheld this year. It won't win back trust, but it'd still be rad as hell.
I'm not confident that any individual studio is completely safe from being shut down, but Rare definitely seems like one of the safer ones. Regardless of all that though, the part about Nintendo buying the IP is what signals this is obviously bullshit. At best maybe fans trying to will something into existence by getting enough people to repeat it, as if Nintendo would make a new Banjo game even if they owned the IP and not just put Banjo in Mario Kart.