I think its natural that their architectures are increasingly focused on server and mobile(not Core mobile but Atom) over PC chips. That's where the growth is. So expect rapid improvements in both Atom and Xeon lines.
When you have an architecture that spans all the way from premium Tablets to $100k+ servers, there is bound to be a point where its less optimal.
I just hope they can find more than 5-10% gain every 2 years on their PC chips as well.