Yeah, I don't think they will ever switch to some PoS, but I may be wrong... There are though some "new" (2016) academic developments with respect to PoS: it's not trivial but it is feasible. This doesn't mean that PoS will replace PoW because they have a different set of strong/weak points, so I think they will just coexist. (I'm also curious about this new proof of space and time, which I believe could be a real alternative to PoW)
You could be right.
But don´t you think that academic developments of consensus algorithms are different to them being
actually viable for a network that secures billions of $ in digital assets?
What if there are bugs that don´t show up in academic theories?
What if there are unknown attack vectors that make it easy to steal user balances?
It is simply completely crazy to switch the consensus algorithm of a platform that
currently has a market cap (I know, market cap is not a great metric for
cryptocurrencies) of nearly 100 billion $. If PoS proves to be insecure or bad for other
reasons a large amount of this wealth could evaporate.
Proof-of-work has been shown to be secure for nearly a decade, PoS has never been
attempted aside from a few altcoins with low market caps.