He said that bitcoin's use of only sha256 for proof of work wouldn't last the year.
He implied that it was because 51% threats from non-economically motivated nation state actors would force replaceement of the current PoW scheme with a "basket" of algs.
Or so I recall from his talk at the conference in May. I didn't check his quotes/writings.
I don't remember him saying specifically a 'basket', but he may have and I forgot.
I'd love to see this happen, but also see the algorithms be evolving and unpredictable, and also have reward adjusted to promote other kinds of diversity. But it would be complex to implement and I suspect that miners would make a credible threat to destroy the system before they allowed that to happen.
Probably the only way for Bitcoin to evolve past today's rather simplistic proof-of-work scheme would be for it to form a symbiotic relationship with alternate crypto-currencies (or spawn a set of them) such that miners could continue to capitalize using sha256 gear. Either that, or leverage the existing sha256 hashing power to re-base (for optimization) the value source-of-truth periodically (with a much longer period than every 10 minutes.)
I'm not holding my breath for that to happen. Or holding all of my BTC for that matter...