What's funny about this discussion is the fact that Linus is supreme dictator of kernel.org. Whatever he decides to merge in his personal fork of Linux shouldn't be up for debate just because the Linux community willingly decides to keep pulling his commits into their clones.
That's why we have the right to fork. While we can't change GPLv2 kernel code, there is nothing stopping anybody from including GPLv3 code in the kernel so long as it doesn't directly link against GPLv2 code in a way when the fork is distributed.