No, the argument I was making does indeed fully generalize to the entire category of Proof of Stake solutions. The goal is to create a dynamic membership set signature, meaning that people can come and go by some mechanism. But that requirement enables simulations because if the future membership set can’t be predicted, then neither can alternative past histories be differentiated. Then no matter the construct used, with enough sybil identities anyone can grind variations on history until one is found which benefits the one doing the work. In this way any proof of stake system devolves into proof of work, only with worse properties (since if you're going to have proof of work anyway, double-SHA256 is about as good as it gets).
Furthermore, because the incentives are structured such that grinding histories is profitable behavior (and it needs to be for the system to be secure, since it is the same incentive that protects proof of stake when people follow the rules), you can be assured that unscrupulous people will grind histories, and others will too because the alternative is losing out. So proof of stake is NOT any less expensive than proof of work, because any proof of stake system becomes proof of work.
The solution to the mining centralization issue has nothing to do with proof of work algorithms or ASICs. The solution is things like smart property miners, coinbase-only mining, and delegated transaction selection. These are being worked on.
Vitalik says cryptocurrency developers should "reach out to LessWrong more", in order to not be ignorant of advanced computer science and game theory topics.
https://blog.ethereum.org/2014/12/31/silos/
I think Vitalik raises several major important points, namely:
* Bitcoin's $600 million wasted on electricity yearly in order to secure the network is a huge problem. Various Proof of Stake algorithms are attempting to improve upon this. The ideal solution would be one which combines the low cost of the Proof of Stake algorithm, with the high security or Proof of Work. I not enough of an expert to be able to say which solution is best, but both the Ripple consensus algorithm and the Bitshares Delegated Proof of State algorithm look promising. I am interested to see what algorithm Vitalik will choose for Ethereum.
* ASIC miners are a problem due to the resulting centralization. They have also lead to increased centralization in Bitcoin, as the network is now increasingly controlled by a few large mining pools.
* Blockchain technologies have a great potential to change the world, and solve governmental and organizational problems that society is facing. Beyond simply revolutionizing money, blockchain technologies could also be used in the future to support prediction markets, voting/consensus building, exchanges, etc.