Lets not forget how centralized ETH is becoming with the PoS upgrade. It's worse than it was before. With Vitalik having huge influence over the project, as well as, large ETH holders, Ethereum would be nothing but doomed. I now understand why there are many Bitcoin maxis out there. No other coin can outmatch the "King" in terms of decentralization and censorship-resistance.
If Vitalik would've wanted Ethereum to become another "Bitcoin", he would've remained anonymous from the very beginning. He would've also refrained from turning ETH into a centralized PoS "shitcoin". Keeping the good-old "Nakamoto Consensus" (PoW) algorithm would've been the smartest decision to make. Unfortunately, human greed has led ETH to where it is right now. It's all about making money these days. ETH will survive but it will never be as good as it was in the early days. All good things come to an end, right?
I think it is not really the amount of ETH one ones, but more like if the public doesn't want a change, then they won't and no matter how much ETH you own, if public decides not to accept it, they would continue to use the old chain. Remember, you can't make a chain disappear, its always there, even legacy bitcoin is there, but we use segwit.
I think it would be quite obvious that there is no centralization in "power", because people still have it. There is this questionable situation, because whenever Vitalik offers a new idea, people accept, so while people CAN reject, I have not seen it, so you can call it centralized in that sense. There is a "leader" of it, and that's risky, but the blockchain itself is decentralized.