The days when Intel could single handedly successfully introduce a new (incompatible) ISA are long gone (if it ever could). I expect they will stick with x86 for as long as possible.
Itanium underdelivered on performance both in its native mode and in x86 emulation mode. Either of them could have tanked that design by themselves, but both applied.
There was also the three way ISA battle at Intel: 486 vs 860 vs 960. In the end they decided that legacy software was too valuable and redefined the 860 as a graphics co-processor and the 960 as a intelligent DMA to keep people from building Unix computers with them
