There is no indication that OpenAI won't honour its commitments to Microsoft, and I think it's incredibly unlikely that said commitments to Microsoft had anything at all about keeping Sam Altman as CEO.
Their stock is probably up $250B because of this investment...
The idea they're getting screwed is interesting.
Microsoft is a lot of things - stupid and incompetent are neither of those things.
They want to have their cake and eat it, too.