I am not a TCA member up until this point, not much of a joiner in general, but from my outsider's perspective I see a couple of things here that if I was one of those running the TCA I would be concerned about. The first is that many have said outside York, there wasn't much to the membership that interested them, that they aren't into pre war and post war and the like. That makes sense that the TCA first and foremost was a collectors group, but maybe kind of like OGRR changed from being 2 rail scale to primarily 3 rail, they need to change focus and embrace other things (yes, I realize there is LOTS and other operation focused groups....). The museum is great, the library is great, but maybe the real problem is York overshadows everything else because that is all most people see of value...not criticizing the leadership, running something like the TCA is about the most thankless task I can think of, outside of doing a church newsletter.
For those who see York as the only benefit (which I can understand), given how many people have said York is what it is pretty much about, what happens if people leave TCA, disgruntled that York didn't happen? I don't know all the ins and outs of how the TCA or York is set up, but I suspect it is likely if the national TCA starts hemorrhaging members, York may not happen, not enough volunteers to man it, financial support they give, etc. I don't know how TCA national is vis a vis york, but in most of the groups I have belonged to (the few that I do), usually the local group hosting events, especially big ones like a national convention which York sort of is, get money that comes from dues across the organization (I know this from a car club I belonged to)....so in a sense, as a York attendee you get that benefit out of it, whereas the person who can't/doesn't want to go to York , doesn't use that benefit, is helping subsidize those who do.
The point is that York is one of many benefits of belonging to TCA, it isn't TCA, and by withdrawing membership because York isn't there could end up meaning it doesn't happen in the future, either, because National may not be able to do their share with York, whatever that is (if York on the other hand is totally independent of national, the people running it don't get anything from national dues, just their share of local dues, then this wouldn't be true, though if national membership declines fewer people would go to York, and it would be a death spiral, others seeing less people there, would pull out of TCA saying York wasn't worth it......or the show would *gasp* become a totally open show, with nothing special for members.
Again, I don't have an iron in the fire with this, I don't belong to TCA because with where I am right now, I likely wouldn't get any benefit out of it, I don't go to York (never seem to be able to get the time to go), not really a collector and not much for belonging to a local TCA group...but even if TCA to you means York, then realize staying a member can mean future shows happening because it keeps TCA itself afloat. I have had tickets to performances at a local performing arts center (a non profit) cancelled because of Covid, and rather than get a refund I turned my tickets into a donation so they could keep the place limping along until better times returned.