My 2009 iMac has a first-generation Core-i7 chip that has 42-nanometer circuits. I just bought a refurbished laptop with a Core-I5 that has 35-nanometer circuits, and it performs 80% as well as the desktop even though it has half as many cores.
This is an interesting website about microprocessors. I don't think that I would want to buy a processor with a 10 to 14-nanometer process when 7-nanometer processors are coming from AMD in August. I find it interesting that Apple introduced 7-nanometer chips in their phones many months before either major processor company came out with 7-nanometer processors. I also find it interesting that both the new Play Station and the new XBOX will have 7-nanometer processors from AMD.
In terms of the laws physics, it is almost impossible to get much smaller than this, although I have heard talk of a 5-nanometer chip. I also heard about a possible 1-nanometer chip using different materials, but the technology is a long way off, and I have my doubts about how well it could work.