Sometimes I wonder if IA-64 was just an exercise in killing of Alpha and HP-PA...
Anyway, x64 succeeded because instead of producing something no one asked for, and poorly (IA-64), AMD went to Microsoft, found out what they wanted from a 64-bit chip, and built that.
If Intel had transitioned their processor line to IA64, without AMD to defy their roadmap, do you really believe consumer desktops would magically start using other vendor processors?
> AMD went to Microsoft, found out what they wanted from a 64-bit chip, and built that.
Because they still had the cross-license deal with Intel that allowed them to legally build x86 clones.
No x86 licenses, no x64.