Other way round: the only way any company other than Intel was able to get a new instruction set launched into the PC space was because Intel face-planted so hard with Itanium, and AMD64 was the architecture developers actually wanted to use - just make the registers wider and have more of them, and make it slightly more orthogonal.
In that different world, Transmeta would actually succeed in the market of x86-compatible CPUs and, perhaps, would even come up with their own 64-bit extension. Itanium would still flop.
Or maybe, if the push came to shove, the desktops would switch to something entirely different like Alpha. Or ARM! Such event would likely force ARM to come up with their AArch64 several years sooner than it actually happened.
