Intel and HP only failed, because AMD exists and was allowed to design chips that provided an alternative to Itanium.
Without AMD, the market would not have spoken anything.
Without AMD, the market would not have spoken anything.
What authority do you propose to gate who is and is not allowed to design semiconductors?
The x86 ISA started at 8 bits, sharing design elements with an earlier 4 bit device. It was successfully extended first to 16 and then 32 bits. Extension to 64 bits was inevitable. The fact that a hungry competitor fulfilled this inevitability before the market forced Intel to do so is an interesting detail and little more. The fact that this obvious evolution was all that was necessary to wipe out Itanium is telling.
Intel 80x86 architecture was successfully to 16 and then 32 bits, by Intel.
Intel would have been forced to extend x86 to 64 bits sans AMD. The market wanted address space. It did not want a "better" ISA, a new programming paradigm and all the other junk. The part of Intel still listening to customers understood this and Project Yamhill (Intel's 64 bit extension to x64) was underway at least a year before the first AMD x86_64 device appeared and after the first Itanium devices were sold. They knew they had a product the market didn't want and started moving to 64 bit x86 before AMD even delivered their first K8.