I've seen in multiple places project owners choosing to stick with GPLv2 to prevent the FSF from releasing a license that the project owners don't agree with but I've never seen reasoning beyond the claim that the next GPLv4 could be disagreeable. Are there any real licensing dangers associated with this ability to seemingly change your project's license at will?
For example, if the FSF were to release "GPLv4" and it's just the exact text of the MIT license what would happen to projects that are licensed under GPLv3+? Could they be licensed under the terms of "GPLv4"? Are there restrictions within the GPLv3 that prevent this from happening?