My sister (early 40s) and her peers are still using it on a regular basis, but the content could easily be on twitter or instagram.
The real demographic that is in love with it is my parents' generation, ~67+. They follow a lot of the '%city% then and now' and other nostalgic groups. Along with those, their feeds are filled with goofy videos that were going around a while ago.
I don't see Facebook going the way of myspace in the near future, but I do think they'll have to shift their focus a little if they want to draw us back in.
What I don't understand is why facebook isn't going head first into online dating. They already have a lot of information on everybody -- where a lot of us like to eat, locations we frequent, events we like, etc. For a lot of us the data would be slightly outdated, but I bet they could give some solid suggestions.