"However, proof of stake, as implemented in nearly every currency so far, has one fundamental flaw: as one prominent Bitcoin developer put it, theres nothing at stake."
It turns out that isn't a problem.
Do you think Ethereum could be the PoS system that suceeds?
I don't know much about Ethereum, but I believe it is not currently planned to be PoS. Generally, about half the top-10 coins are PoS; isn't that success?