Making processors is getting very expensive. According to this report, the R&D to take a processor design and turn it into something that can be fabricated at the latest silicon mode is $1B.
Each fabrication node (where the transistors shrink) has gotten more expensive. I suspect it’s likely that economics will play as big a role in killing off Moore’s Law as physics will. Eventually no one will be able to afford new nodes, even if they are physically possible to create.
This is what an s-curve looks like.