That's definitely not how its written or interpreted. Microsoft had to release code because they touched GPL code some years back I think it was for HyperV? We're talking about a company with many lawyers at the ready not being able to skirt the GPL in any way, like undoing the code.

Additionally, in order to CHANGE the license, if others contributed code under that license, you would need their permission, on top of the fact, you cannot retroactively revoke the license for previous versions.