Do I worry about our hobby dying...not at all. What I do believe is that it will probably change with time, like a lot of things do. When I was growing up in the 80's and 90's, collecting baseball cards wasn't something you did because you thought about the amount of money a card was worth or resell necessarily, you did it because you loved baseball and being able to collect your favorite players and team made it worth your while. It's a lot different nowadays...a great deal of people are solely in it for the money. There are people on this site that don't give a lick about baseball...couldn't tell you much history about the game throughout any decade, but they have stellar card collections...this is what worries me. Card collecting has become a money thing more than collecting, but I can't blame anyone as this is how the hobby has shifted for the most part. Card collecting used to be simple and enjoyable, now it's mostly about money and a card collector that actually does so for enjoyment is a rarity.
Me, personally...I don't think much about the state of the hobby, I'm just enjoying the ride. I will attempt to get my boys to like sports and possibly ball cards, but this isn't something I will try to force them to do. They are growing up in a different era and looking back, it was a whole lot different than thirty years ago...cards were easy to collect, a lot of kids collected them, they were relatively cheap to buy and you could do anything with them and have fun! Today everything is so condition sensitive, it drives me nuts!
I still collect modern cards, mainly a few players that I enjoyed when I was a kid...nothing like turning back the clock or obtaining the cards that you never thought you would be able to when you were a kid...priceless!