I think improved horizontal scaling also had a big role in killing off Itanium as well as all the traditional RISC vendors. Load balancers, high throughput local networks, distributed caches, etc, became common and reliable. Which pushed the purchases of bigger RISC servers to niche things like huge database servers.
That left little room for Itanium to be cheap, because it was competing only in the high end, with less economy of scale, more expensive peripherals, etc.
An enormous amount of effort, some small corner of which I was involved with, went into vertically scaling x86. And, at the end of the day, it was pretty much a waste of time, effort, and money.
That left little room for Itanium to be cheap, because it was competing only in the high end, with less economy of scale, more expensive peripherals, etc.