Well if it means that AMD couldn't ship any x86 processors and Intel couldn't ship x86-64 (i.e. AMD64) processors, that effectively means neither of them could

Well if it means that AMD couldn't ship any x86 processors and Intel couldn't ship x86-64 (i.e. AMD64) processors, that effectively means neither of them could ship any modern x86 processors at all, so that's effectively mutually-assured destruction. If that were in any danger of happening I'd bet dollars to donuts it'd be renegotiated immediately since they both stand to lose everything.