There is a simple solution to "democratize" mining;
adopt a PoW that takes at least a GB of memory to solve
(with no time-memory tradeoff) and that depends on latency rather than bandwidth.
That would put an end to specialized mining hardware.
scrypt?
No way, scrypt only needs a lousy 128KB, and even with that is very parallellizable.
Technically, it's not even a PoW since verification is a nontrivial computation,
and that only gets worse when you try to increase its memory footprint.