It was certainly a difficulty, but I suspect between ecosystem work and iterating on the processor design the market *could* have made it a serviceable ecosystem.
While the technical challenges certainly further embarrassed itanium, the main issue is that it demanded recompilation and users weren't exactly in a rush to recompile for the then hypothetical concern of only having 4GB of ram per-process. Well before that became a practical concern, AMD64 arrived.
Itanium sucked and no one wanted it, but if it *had* been the only multi-vendor option for reasonable large memory support, the market would have figured it out. Thankfully Intel wasn't the only company allowed to implement x86, or else we probably would have been stuck with a terribly awkward transition and putting up with the warts. If AMD64 didn't happen, and Itanium was truly unfixable, then maybe someone would have made a run at higher end MIPS64 again, or *maybe* PPC, though I think IBM would have never found the will to do that with PPC including letting their competitors use it.