So instead a cartel of miners you'll get a cartel of crypto-banks and exchanges with lots of coins in their cold wallets for which they'll additionally earn interest, without having to reinvest in new generation hardware. MtGox would have dominated a PoS-version of Bitcoin quite exclusively back then.
Not that I know of any better solution, concentration of wealth and power seems to be a general problem inherent in capitalism, or possibly even any imaginable form of human society.
I forget, miners being forced (if they want to remain competitive) to continually throw away old hardware and but new hardware a positive thing?
And yes, people with larger balances that they can stake will earn more than people with smaller balance, but everyone would have the opportunity to earn proportionate to their balances,, rather than the mining world which is getting more and more consolidated.
If it's just about income, people will migrate to services that share more of that income with their depositors/investors, or else be actually motivated to hold their own coins.
If it's consolidated power, such a set up would allow the community to have a say; if they saw that one exchange or wallet service was accruing too much power, it would be trivial to shift their coins elsewhere to balance things out. Far more democratic than the mining cartels were or are. Way back when, we basically had to take friedcats word that ASICminet wouldn't account for more than 30% of the network, but no way to keep them in check.
None of this sounds bad, and in fact sounds preferable. If course, there is huge vested interest that will be opposed to such an idea. Mining pool operators. Miners themselves. Who will either say if you want POS, go for a different coin, rather than try to envision a way forward fir Bitcoin itself; I still think that ASICSZ were detrimental to the community, as it drastically reduced the democracy of the ecosystem, replaced a single investment in a set of GPUS with a never ending cycle of buying newer and newer asics to what end? Security? I don't think the network is anymore secure if it requires an attacker to invest $2bn in Gpus rather than $2bn in asics