It is all what ifs by now, however I firmly believe if there was no other option other than Wintel, Intel would keep pushing Itanium and sort out the design issues.

The thing with AMD64 is that now there is this myth that there was no other alternative than keeping up with x86, and Itanium redesigns for some magical reason were impossible.

Other than those redesigns never happened, because AMD64 made economic invalid to pursue them.