We have a pretty good understanding of physics in this area, and one that has stood many significant tests. While it's of course always possible that we're miss

We have a pretty good understanding of physics in this area, and one that has stood many significant tests. While it's of course always possible that we're missing something, it's entirely likely right now that there is no new physics to be discovered at the scale of microprocessors. Given that, we have a pretty good idea of how much more could be done in principle to improve processors (if we assumed we could overcome all engineering challenges), and it's not that much more.