Re: "Intel's deep history of innovation failure"
There are at least two good reasons for ditching a big hairy old ISA:
1) It's far quicker, easier and cheaper to design an implementation of a clean, small and well defined IDA vs a very complex very old & crufty ISA.
2) It's far quicker, easier and cheaper to validate an implementation of a clean, small and well defined IDA vs a very complex very old & crufty ISA.
Those two reasons underpin why RISC architectures continue to survive and thrive through domination of the SoC scene - which happens to be where most of the money is. Shipping big clunky and expensive 2000+ pin packages is dandy - but it doesn't cut it when folks are trying to sell a couple of million mobile phones.
The most damning indictment of Intel's innovation failure is that it was *AMD* who developed the current dominant incarnation of x86 (AMD64 - remember that ?). Just to add a bit of salt to the wound there were senior Intel engineers posting on USENET sometime before Itanic (2001) saw the light of day that stated they reckoned a 64bit cut of x86 was what folks wanted (and was very doable). Not to mention that the whole dynamic / static optimization argument had already been decided by the Alpha EV6 (1998) vs the EV4 (1992).