Today, a majority of BTC is traded and custodied on CEXs. With the advent of ETFs, in the long term BTC will effectively be controlled by a few regulated CEXs. Might as well cancel PoW and go PoA - it'll actually be more decentralized than 2 mining pools & a handful of profit-maxi centralized mining corporations.

PoW (or PoS) are useful for forming a status quo. But beyond that certain point, due to economies/entrenchment of scale & lack of redistributive mechanisms, they will likely only centralize things further. When the time comes, replacing them with a better mechanism will be essential for minimizing centralization.