Our architecture with the current epoch of technology (silicon based chips) gets closer and closer to atomic limits every year. Engineers come up with ways to get around them, but these come with problems of their own and can only take us so far. Moore's law is obviously not a physical or scientific law, but just a self-fulfilling prophecy based on Moore's observation.
Quantum computing is interesting, but is still an indeterminate distance from being practical for consumer electronics, and has a limited range of uses.
It seems like optical computing that utilizes photons is the most promising, as there are minor research breakthroughs all the time, and unlike quantum computers, practical & working optical based devices have been around for a long time.