All good points. Reality is best faced head on. At 53, I am also probably one of the younger collectors out there, yet I have an adult son who (with is wife) is an active RPGer who paints and collects those miniatures, and he still reads everything from Kenneth Roberts to CS Forrester so the future can't be all bad!
I have long since decided that all of my hobbies are in their post-Golden Age twilight:
1. Toy soldiers (toys, not military miniatures; I like British hollowcast)
2. Mid 20th century miniatures by Rose, Stadden, G&B, Imrie-Risely, Scheid, etc...
3. Tobacco pipes (try that with the Millennials!)
4. The novels of RF Delderfield, Evelyn Waugh, and any book by RM Barnes or the Funckens
Oh, I like drinking Rob Roys, too.
It could be worse, we could all be obsessed with this hobby and be in our twenties - imagine what it might shrink to by the time those folks have grey hair.
Cheer up and let's play with our little men and horses.