Geoffrey Hinton has recently been talking about how analog and "imperfect" computing with specialized hardware/circuitry may yield much cheaper neural nets, that could easily be as large as human brains, but would only cost a few dollars and would be extremely cheap to run. Not a new idea, but it is a fairly promising outlook, I think.
https://www.zdnet.com/article/we-will-see-a-completely-new-t...