It is never too late for another copmany to join in. Esepcially since Intel has been neutered in its dubious practices
Microsoft's willingness to conform is the key. Which they are doing building windows 8 to run on ARM processors. If ARM decides to go desktop, which all indicators are pointing towards it is AMD that is more at risk than Intel.
I don't think AMD will disappear however. The Llano APUs are amazing and FAR better than anything Intel develops. The PR videos are not wrong. they avoid the uniformed HWBOT benchmarks, that favor Intel and nVidia, instead focus on real world usage, and the Llano dominates that, smooth scaling with multiple tasks running.