I noticed on myself that my activity on forums dropped to almost zero over the last two years, it was quite high before that (gradually dropping while I was working on my diploma), well... I finished it, and started doing more business and less game development, less (non-job related) graphics development, etc.
So I slowly got to the stage where I noticed that I'm starting to be separated from game development, which lead me to a point where I realized I don't want to live a life without making games. Since that point I did two entries to last 2 Ludum Dare competitions ... even though I love making tools, fine tuning my game engine source (which I have actually never used for game), etc. ... I used Unity for that. Anyways - a game is a game.
Nevertheless, to keep myself connected to game development I decided to start doing a journal here, regarding my development ideas, thoughts, post mortem articles and maybe even some progress from time to time. And most importantly, code and articles!
I am sure most, maybe there are a lucky few that haven't, developers have been pulled away from games or the part of game development they are passionate about at some point in their careers.
It comes down to how you return to the scene and if you can muster the will to force a game up onto the stage for people to see.