I suppose that PoW and PoS in their current forms are both susceptible to 51% attacks, just in different ways.
I like the concept of PoP as an alternative to state-issued identification, but I worry that it is effectively exchanging security for privacy in the grand scheme of things. It's sort of counterproductive for the goals of XMR in my opinion, especially for a privacycoin.
Maybe a dual dPow-PoS system could be the most beneficial solution. It could also be interesting looking into Proof of Burn.
