You make a good point that PoS would solve one of the issues I raised which is electricity usage.
In theory it could also increase throughput and reduce costs, but: a) in practice that hasn’t happened yet despite years of development, b) it’s never going to be as efficient as a centralised system because of the extra overheads necessary to decentralise it, so that point still stands
All my other points still stand as well, plus the additional problems PoS creates to do with centralisation of power