First of all, welcome to the board, Bob.
I like the answer of "who is going to buy our cards in 20 yrs?" as being "me", the best. That being said I believe like the rest of the folks have said, it will be the people that migrate backwards from today's cards as well as those people that like the game, are collectors by habit, and start to have more disposable income as they mature. It's certainly true that kids today have a ton more options for stimuli
available to them, than us baby boomers did. I still get a kick out of all the excitement which that recently shown 1937 Kendall Gas game of baseball players advertised, by only collecting the stamps!! It's classic. best regards