We get a lot of threads like this. It isn't uncommon. I think age is one of many things that drives the ebb and flow of your life, and how gaming fits in it, but there are other factors - children, relationships, work, finances, other interests etc...
At the age of 42 I do play a lot less than I used to. I've accepted that and I ignore the pressure to play all the latest and greatest titles. I upgrade my hardware less frequently, but I still try to get decent stuff when I get round to it.
I put a lot of it down to having a family - they keep me more occupied than I would have been as a younger man, and by the time I sit down in the evening I want to spend it in the pleasant company of the lovely Mrs bfar, who isn't really into gaming herself.
Every once in a while a title comes along that I can bury myself in, and it's still very satisfying.I casually play some console games with the kids too, which can be a laugh, but it wouldn't necessarily be stuff I'd choose myself. I'm certain as I get older and the pressures of family life ease (which is already beginning to happen) I'll start finding more time for games and other hobbies.