@kynes Backward compatibility is an undeniable advantage, but I don't think it's a requirement to reach the domestic market. We have the example of ARM that occasionally makes incursions into desktop computers (with Nvidia's Tegra boards for example) and that has managed to take a small bite out of laptops with Chromebooks. In fact, even Microsoft released a Windows ARM although later they decided to abandon it.
The truth is that I don't know to what extent IA-64 would have contributed something interesting to the current IA-32 + ADM64 (x86-64), but what I am almost certain of is that having maintained a niche like high-end servers with only HP as the assembler has killed the architecture and more so with a monster like IBM overshadowing it in that segment.
By the way, Intel has said that the replacement for Itanium will be Xeon. Let's see if they give a boost to x86 that, leaving aside the physical limitations of manufacturing, seems that lately they are not making great achievements.

