@wonka @osma @ghul @pkal GPLv2 explicitly allows any later version, and removing that is an additional restriction so dubious. It would take a court to sort that question out however, and for Linux it's not likely to ever happen.
More importantly though was also the social contract. Linux was built and people contributed on the GPLv2 basis. Changing that would have been shutting doors on existing contributors. That point to me was the salient one Linus made when GPL3 arrived