The real problem was that they just had significant layoffs as part of Microsoft, and before then were forced to make Call of Duty content under Kotick's Activision.
I suspect they're imagining that 'security' is overrated in this situation.
Wish them luck, though. They'll need it. Probably the safest path ahead is to stick to known IPs for a while...probably why they want to work with Microsoft. A newly independent studio stands a better chance with a Crash or Skylanders game than an unknown IP. Best to play it safe in this climate.
I imagine they'll start with an IP Microsoft own (probably that rumored Banjo-Kazooie game...although that would be better as a BK/Spyro/Crash mash-up IMO especially looking at sales for Crash 4 not being too hot), but I'd be very surprised if they only work with Microsoft going forward. Nintendo, Sony, EA, Take-Two, Sega, Capcom, Square-Enix, Bandai-Namco, Devolver, Annapurna....the floodgates are open now for possible additional partners for them to do business with freely.
Still find it a bit odd that MS spent $69+ billion on ABK (including TFB), only to near-immediately make them independent. It kind of does show their pattern of using M&As to target IPs but not so much to retain talent. But I digress.
But they aren’t on a retainer. TFB can choose to partner with Microsoft on a project, or another company, or no one at all.
Sony or Nintendo could buy them tomorrow.
They could, but I highly doubt it. I can see either or both of them, especially Nintendo, partnering with TFB on a spinoff platformer however. It almost makes too much sense.
Look at what TFB were making before they became a COD support studio. Nothing but Spyro, and a little Crash, for 12 years. It's what they do and it's what they're gonna continue to do - make a Spyro 4 which Microsoft will put on other platforms because it's exactly the sort of thing that will sell well/better on Playstation.
Like Banjo said, chances are if they are going independent, it's partly because (assuming they had a say in this, anyhow) they want to do IP beyond just Crash and Spyro. Whether that means their own new IP, or IP belonging to other companies, TFB seem like they're up for it.
They specialize in 2.5D and 3D platformers, so I wouldn't be surprised if Nintendo or even Sony do in fact decide to do a game with them in the future, or other publishers like say Capcom or Sega, or even other 3P devs in a collab like the It Takes Two developer. You don't go independent without wanting to "stretch your wings", that would include working on IP beyond the ones you've been tied to for the past decade.