GameSurge has a short article taking a look at the 'future of quake' and the staying power the series seems to have. I do believe Tim Willits was quoted in a chat a while back stating that there will be no Quake4. Last month Graeme was talking about his inspirations for the next id Software game, which seems to be pointing in that same direction. It certainly doesnt look like Doom2000 either, hrmph...