Oh boy... I'm younger than most of you, but I think about this all the time, especially since I have no children or anyone else to pass things down to. Unfortunately my only niece (who is 20) did not inherit any crafty genes from my side of the family.
All I can say is, over the years if I've decided that I'm not going to do a particular craft anymore, and I get rid of that stuff, I have always regretted it. About 20 years ago I said I was too slow a knitter to continue and got rid of everything knitting related. So what am I doing now? Knitting, of course. Still slowly, but still enjoying it.
So if I can possibly find a little nook or cranny to keep my stuff, I keep it. The things I use the most get prime placement, and everything else is not so easily accessible. But I've become very creative with the use of closet space.