By what measures hasn't that happened already? CUDA been around and constantly improving for more than 15 years, and there is no competitors in sight so far. It's basically the de facto standard in many ecosystems.
So while Intel had to bow to AMD's success and give up Itanium, they weren't then limited by that and could proceed to iterate on top of it.
Meanwhile it'll be a cold day in hell before Nvidia licenses anything about CUDA to AMD, much less allows AMD to iterate on top of it.