I don't think it's dying, but a lot of people have slowed down. There are a mixture of reasons, but I'd point mainly to a lot of people getting older and completing certain collection goals, high prices on certain items forcing people to pace themselves more, and general tightening of the belt due to economic factors outside of gaming.
In my case, I'm 35. Plenty of stuff I still want out there, but I have to take into consideration that my cost of living has been going up, a lot of the high priority stuff I want is in the $100-200 range now, etc. I'm still enthusiastic, but I'm also trying to PLAY the games I have and not worry so much about what I don't have, and I've never been the type to collect games I don't want to play or have any specific affection for.
TLDR: Quality over quantity!