Has it ever occurred to anyone the x86 viability roadmap is coming to an end, even with multiple cores?
Has it? I can't see that anywhere. I can see false moves with Intel's P4 and - even more apparent - Itanium's 64 bit approach (not a bad design for a start, but bad migration path & marketing) . But AMD's 64 bit move has put so much fresh air into everything x86 that it's here to stay.
x86/64 is absolutely dominant in the professional segment, the home computing & gaming segment and super-computing. If Intel's plans work out it'll even dominate the embedded market but that remains to be seen. IBM's Power has some niche it still defends, but nobody knows how long that's gonna last. Everything else is pretty much dead or dying - PA-Risc, Alpha, Sparc. ARM & MIPS have conquered their markets but not without threat from x86.