All of the current alternatives to silicon are currently of nothing more than scientific interest due to the fact that silicon has been around for so long, is so well understood, manufacturing and using it in microprocessors is such a massive industry, and it's still currently Good Enough. To transition to something like cubic boron arsenide, or carbon nanotubes, or something else will require an incredible paradigm shift in both microprocessor design and fabrication. Guaranteed there are research departments in universities and companies figuring all this out, but much like alternatives to lithium ion batteries, we won't see them anytime soon.