The research papers from 10, 20 or 50 years ago are at least as valuable and frequently more valuable than the papers from this year.

A lot of "new" discoveries are rediscoveries of old things, which may have been not important at the time of their initial discovery, because in order to be useful they depended on advances in other domains, but when those advances happen, suddenly they become important and they can be the base of state-of-the-art techniques.

Therefore Sci-Hub remains very relevant, as a repository containing a very large number of historically-important research papers, including many research papers from the 19th century or early 20th century, which should have been in the public domain, but which can still be found behind paywalls elsewhere.