I think the hobby, and growth in general, is solid. I attend several coin shows along the east coast each year (as a collector, not a dealer) and see quite a few young collectors thumbing through three ringed binders pulling out coins to set aside. As a collector of fifty plus years I certainly relate to the many changes in that time, which simply put is what modern collecting has become. A change, or shift if you will. Which is not a bad thing. Finally, as an ANA member, their own blog page is full of young collectors sharing roll and change finds with an extreme passion which is the foundation of our hobby.
The hobby has been around for a long time and will continue to be. As always it is the quality and not the quantity, the coin and not the slab.