Well, despite what Musk did, X (Twitter?) has still been limping along for quite a while now. While more abrupt and surprising, this doesn't seem nearly as bad as that.
As for Microsoft, if they let OpenAI go, then what? Does Google pick them up? Elon? They are still looking to invent AGI, so I'd be surprised if no one wants to take advantage of that opportunity. I'd expect Microsoft to be aware of this and weigh into their calculus.