There is just no way to keep things decentralized when money is involved. People just need to accept that and move on.
At some point, either after enough halvings or if the price drops enough, it will no longer be cost effective to mine bitcoin on a large scale. At that time all of the mega mines will close up shop and we will be back to small-time "home" miners securing the network. I cannot see any other way bitcoin would ever go back to "the way it was".