Itanium Pros:
Very fast
Itanium Cons:
Very expensive for all current implementations
Incompatible with x86 or PowerPC (completely unrelated instruction set, although there is a pretty decent emulator)
Overall, I'd say it's Not Gonna Happen. It'd be pretty cool (2700 specfp... mmmm....), but it just doesn't seem practical. Intel would have to start selling them at very drastically reduced prices for it to even begin to be practical (like knocking >$1000 off the price of each chip).
<edit> I suppose I should amend this to say that I think it's certainly possible for the future... but not for the near future. Intel won't be able to kill off x86 for quite a while; possibly the only way they could do it is if IA-64 (Itanium) gets enough of a performance advantage that it could emulate x86 at close to native speeds, AND gets price parity with x86. I believe it can currently emulate around a 1.5GHz Xeon, which is not bad, but not great. </edit>