My town still has quite a few third places (the mall, bowling alleys, bars, etc.) and even some new ones like a trampoline place. Most of them are struggling because the young people don't go out. Go into a corner bar on a Saturday night, and you'll see more people in their 50s than 20s. The pool league that used to run 6 divisions a week is now down to 2.

So as far as I can tell, people (especially the young) stopped going out, and then third places started going away.