There will always be 1-3 large pools of more than 20-30% of hash rate. It's just natural incentive. People will always mine where they are most rewarded. They will be most rewarded with the most competitive pools. When a pool starts to get to large the pool becomes saturated. So, some people will point their hash at the next largest or most profitable pool and the cycle continues. It will always be this way imo and there's nothing wrong with it. Mining "decentralization" is a psyop. It doesn't matter if the hash is centralized in a pool. Miner decentralization only matters physically, geographically.