Are they disappearing, or are they actually becoming more prevalent, dividing the population and leaving few people around to support each third space? A third place needs to more than a place – it also needs people.

I can think of 10s, maybe even hundreds, of third paces I could theoretically go to within a short distance. None of them particularly appealing, though, because they don't have enough people to create an engaging environment.

If these third places consolidated their efforts, seeing most of them disappear to focus on one third place, there is a much greater chance that the single community would thrive. Combined, it could be huge, but so long as they each try to go at it alone...