You cannot retroactively relicense code - only new code. Microsoft can just take the last version that's not GPL.
This is why if i were making an open source project, it will start off with GPLv3, with a commercial paid license if anyone wants to avoid the terms of the GPL. That gives the best of both worlds - open access to anyone, and if they want to modify, they must also be willing to contribute in some way.
This is why if i were making an open source project, it will start off with GPLv3, with a commercial paid license if anyone wants to avoid the terms of the GPL. That gives the best of both worlds - open access to anyone, and if they want to modify, they must also be willing to contribute in some way.