On Sunday, October 16, 2016 at 3:56:23 AM UTC-4, RichA wrote:
Electronics, ham radio, amateur astronomy, microscopy, stamp collecting,
woodworking (most of it), metal working. The millenials and teens only want to
play video games, text on their cellphones and go to restaurants to be seen.
One growing hobby is metal-detecting because of the desperation of the fading
middle class.

Quite a number to choose from and some are rather new:

http://discoverahobby.com/listofhobbies

And it's certainly NOT a complete list.