From the beginning, this has always been a possibility: A banker who can effectively create unlimited fiat money can easily acquire all the mining infrastructure and control the network hash power (Of course he don't need to do so through one single entity, it will look like that many people control the mining infrastructure, but when a vote happens people will discover that over 90% of hash power is controlled by a few entity and can go against majority of people's will)

PoW method is vulnerable to large capital taking over. This is the nature of PoW, so some people have suggested to use a PoW+PoS hybrid model for the future mining, but without major hash power, how do you implement this change into the network? Why miners should give up their dominance power today? It seems only a fork or re-design of a new coin can start afresh