The same problem might exist with other patent clauses, though - is the Go one compatible with GPLv2?
Because the kernel is GPLv2 only, you also can't embed the GCC JIT, as it's GPLv3.
So essentially, you are screwed along multiple axes
"but perhaps someday there will be a use for a JIT in the kernel, that we can't foresee."
Maybe, but you can't solve every use case on one side.
(IE it may be that the kernel may have to have some licensing movement as well)
In any case, there are other compilers which would remain license compatible with the GPL2, so should the kernel ever need one it could still have one, I guess it just wouldn't be LLVM or GCC.
Surely, but as you can imagine, the LLVM community needs to figure out whether this is a use case they care about (it was raised in that discussion, and i think the consensus so far has been "not really")