Sorry, Itanium sucks
It avoids these issues only because it is in-order, not because it is better designed. HP's engineers thought a smart compiler could make up the difference for an in-order processor, and sold Intel on the idea so they collaborated on what would have been PA-RISC 3.0 and it became the Itanium. Those engineers were wrong, which is why Itanium has never lived up to its performance processes.
Not defending the turd that is x86-64, but its biggest problem is a refusal to drop backwards compatibility with old shit that goes back 40 years. Drop support for anything but 64 bit mode in hardware, handle 32 bit apps via JIT, and it would be a lot better. If you want a clean 64 bit ISA you should be looking at ARM64. It is not perfect but better by far than either x86-64 or Itanium!