"We plan to do this for a long time. If some of these projects take 25 years, that’s perfectly fine with us. "
Building an institution that supports this kind of long-term commitment is going to be a challenge. While there are plenty of organisations that work over those timescales, very long-term projects seem to me to be unusual - and not just because results are increasingly expected in the short-term, but because 25 years is about half of a long career and few people (imo) have the commitment and self-belief to embark on such a project. I can think of some, like SETI [1] and Mass Observation [2], but they tend to be highly distributed. The danger might be that you end-up with something like the Institute for Advanced Study [3] with its debatable productivity record.
Nevertheless, this is a massively positive announcement from YC. We need more stuff like this.
[1] https://en.wikipedia.org/wiki/Search_for_extraterrestrial_in...
[2] https://en.wikipedia.org/wiki/Mass-Observation
[3] https://en.wikipedia.org/wiki/Institute_for_Advanced_Study#C...