Advances in semiconductor fabrication are no longer increasing single-threaded performance of general purpose CPU code very much. It's still possible to increase performance by orders of magnitude, but it requires giving up flexibility by using dedicated hardware acceleration blocks such as tensor cores, plus going massively parallel with various combinations of SIMD and threading. That all makes software immensely more complex and less portable.
Doubt it, but it is possible. I’ve seen a few videos on YouTube of people who’ve gotten old computers (such as the OG Macintosh 128k which runs on 68k) to connect to the internet. I’ve even seen people use slightly “less powerful” machines running on a 6502 (such as the Apple II and Commodore 64).
Personally, I think CPU architecture became too complicated for my taste after the 68k. So what?