Very fun piece. It might be interesting to take a longer view. I'm under the impression that pre 10k BC, with small populations and limited "researchers," technologies were occasionally lost. Famously, the ability to make fire and to fish might have been lost in Tasmania. So is it a (the?) core fact of civilization that we are able to accumulate technology while losing essentially none of it. 

Re the first point, I agree. I would tentatively suggest doing something like OpenPhil's worldview diversification, where research, labor, and capital are divided among a few distinct futures scenarios and each is optimized independently. My point in the piece is that I think the current program is a bit under-diversified.