Well it's more likely than you might think over a span of a couple decades...
But, I think if they were to go rogue it would be a matter of forking a GPL-licensed version of the software and continuing development on that under an open license.
But, I think if they were to go rogue it would be a matter of forking a GPL-licensed version of the software and continuing development on that under an open license.
And all this is ignoring that most GNU programs are licensed under a GPL variant and any future version, so they would not need the copyright to upgrade the license anyway.