"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?
Absolutely, didnt mean to imply PoS wasn't a success.
Just googling Ethereum PoS PoW, I think you might be right. They might be a hybrid proof of work system, with elements of Pos design to avoid the centralisation problem.