We are all facing the same decisions right now and there is no right answer (except of course our wives' standard answer to any question about cards: "Sell it all!"). About all I can add at this point is that I didn't start collecting 45+ years ago as an investment and I don't
collect now to make money, I collect because I enjoy it. If my enjoyable little pastime happens to be part of my investment portfolio for retirement in 10-15 years from now, fantastic. If not, I still had a blast playing with my cards and BSing with my friends about it.
Burdick wrote that a card collection is "a magic carpet that takes you away from work-a-day cares to havens of relaxing quietude where you can relive the pleasures and adventures of a past day—brought to life in vivid picture and prose." Good to keep in mind these days.