There are huge concerns over centralization. As it stands 2-3 entities (e.g. Lido, binance and Coinbase) over 50% of all validators. This is due to a mix of issues (no withdrawal making liquid staking very attractive, 32Eth limit leading to hugely inflates numbers of validators and no stake delegation creating the need for off chain pools). I would say there is about a 1-2% chance that BTC adopts PoS on a good day. Based on what Ethereum has delivered it's very close to 0.