My viewpoint is that the logical conclusion is that the AI consciousness or community would be a separate entity from Humans (Homo Sapiens). So in essence we would be surpassed in computing power (brain power), but it doesn't mean the end for Humanity. Humanity could continue to coexist with the version of AI in a civilization that becomes near-utopian. We can't say for sure as everything right now is pure conjecture.
You are correct, though, that our collective intelligence might be left in the dust. The other thing is that it may take generations upon generations of learning-bots to create imagination and creativity. Therefore, we as Humans might still be able to think outside the box while the AI Beings might be limited to a purely logical scope.
Again, all of this is pure conjecture, but an interesting one.
Playing Devil's Advocate on your Block Chain decentralization argument, all I'd have to say is that at the point where AI evolves further than the combined intellect of Humanity, it could be a simple matter of deciphering the methodologies and common pathways of individualized Human Brains. Then, once they decipher these patterns and algorithms, a mere Human object might be able to block a real Human from accessing the Blockchain and the algorithm could become so powerful as to clone the usage patterns. Then it's just a matter of many algorithms running concurrently to sever all connections to the Blockchain in order to mimic every connection. Once that's done, these higher powers could negotiate the world of the Blockchain so as to shut down the entire mechanism and render us a moot point.
Playing Devil's Advocate, AI would probably push us aside and even get around our decentralization attempts quite easily.
That's my 2-cents-worth (or hopefully more if enough people upvote it).
Yes they could do all that if they were smart enough but note that the blockchains are being used to do an ever increasing amount of stuff. Note in a few decades the chains may collectively control much of the world economy. If they were smart enough then all they would have to do is use some smart contract to engineer a world war that had the unexpected outcome of putting the AI (Ems?) in power. That's why us humans must strive to be better, and not to let some small elite take to much power and give it to robots.
This is precisely the point. We can have neither an optimistic POV nor a pessimistic POV since this is so entrenched in pure conjecture. I would much prefer to think that we as Humans, in the coming decade, learn to live and thrive peacefully between ourselves. That in and of itself would show AI that we can maintain ourselves in a manner befitting our species.
Thanks for the discourse, very interesting.