I also think the gipf games haven't had enough time and volume of players to see if they are actually as long-term engaging as chess and go. my speculation is that the classic abstracts are the ones that turned out to have an almost accidental emergent depth that kept people playing them even as better and better strategies were devised, because they were never "solved". it is unclear if yinsh will turn out to have an endless stream of better and better strategies emerge, or if it will be fun while people figure it out but plateau when they do.
The Gipf games have had some two decades now, and quite competitive online scenes for some of the games. They've been played enough to know they aren't broken or trivially human-solvable (Zèrtz on the smallest board option probably is but like most of the Gipf games, it's very naturally extendable to a larger board.) Dvonn and Gipf had strong bots for them even in the pre-MCTS age, but that's not really a problem. None of the Gipf games are drawish.
Whether they become "timeless classics" and get a stream of discoveries or not I think is mostly down to chance. It's more about what we let them be in our lives than their inherent qualities.
