Based on https://en.wikipedia.org/wiki/File:Itanium_Sales_Forecasts_e... it's clear that Itanium was delayed and sales projections were drastically reduced multiple times before AMD even announced their 64-bit alternative, let alone actually shipping Opteron. (For reference, AMD announced AMD64 in October 1999, published the spec August 2000, shipped hardware in April 2003. Intel didn't publicly confirm their plans to adopt x86-64 until February 2004, and shipped hardware in June 2004.)
