I think centralization will not going to happen because of conflict of interest. Nobody will give way and cooperate with this kind of idea. As long as everyone will keep and hold their bitcoin, centralization is not possible.
Probably. However, if big corporations like Bitmain sees a huge opportunity of doubling or even tripling their money with Bitcoin, then they'll do whatever it is to make Bitcoin centralized. I'm sure that many people won't allow this to happen since they prefer Bitcoin to remain decentralized and free from middleman just like Satoshi intended it to be. It will all depend if a consensus is reached whenever to further decentralize Bitcoin or turn it into a centralized banking system like fiat.
Hopefully, with the emergence of new ASIC hardware manufacturers, Bitmain's monopoly would be no more as decentralization is improved. For the benefit of all, Bitcoin should remain as decentralized as possible for years to come. In the future, Bitcoin could remain decentralized if the community and development team work together to make it that way. All the way around it, if Bitcoin fails to achieve decentralization, then it'll be doomed, IMO. Just my thoughts
