I think it is important to remember that PoS systems cannot be a democracy. They are by definition a plutocracy, whatever hybrid forms they may take. Bringing liquid voting in the mix won’t change the fact that this system will count votes based on stake.
I anticipate that one trade-of is that people will more likely base their decisions on rational thinking rather than emotions or revenge precisely because of their stake, that acts here as a proxy for a minimal education on the issue to be voted on.
Until the day we’ll be given a private key at birth, making us crypto citizens by right, I don’t really see how to discuss all these problems under the label of democracy.