A lot of research has already been generated looking for better materials than silicon, asynchronous logic synthesis strategies, post-von Neumann architectures,

A lot of research has already been generated looking for better materials than silicon, asynchronous logic synthesis strategies, post-von Neumann architectures, methods for writing non-traditional, and especially parallel software. If any of them worked we'd be using them right now. They didn't. We aren't. And no amount of research is going to give us transistors less than 30 atoms on a side (we're around 100 now). There will be no chips that signal faster than the speed of light, which means no chip will be able to get bigger than a few centimeters across. Between those two constraints the design space is pretty much bounded.