And nostalgia has helped some games hang on. My box of most Cheapass Games catalog speaks to that. It doesn't hurt that they take up less space than my Ticket to Ride collection :D
But older games like Catan or Ticket to Ride or Through the Desert or Ra or Bohnanza all have a firm place in my collection, not going anywhere, and my oldest cat is younger than the youngest of them. (To be fair, neither of the two tabbies who came from the same litter are that old)
However, to be fair again, I've also gotten rid of a couple hundred games that are that old. I think that what I'm really looking at are games that have really proven their staying power. They're games I've played lots of times and want to keep on playing.
I used to be part of the Cult of the New, trying every new game I could. However, these days, I'm part of the social club of the tried and true. (It's a fair bit less formal, really)
At the same time, I have to admit that I do prefer what some folks call German Family games, as opposed to Euros. And sometimes it feels like there was a golden age for German Family game about ten, fifteen years ago and it's more of a golden age for Euros. I bet there are brilliant German Family games being made right now and I just don't know where they are. Like Bigfoot, only with meeples and cards.
In the end, I'm keeping games that I want to keep on playing. And if I've kept on wanting to play them for years, I've kept them.