There's a John Carmack Q&A on GameSpy.com and a Tim Willits Q&A on HomeLAN Fed catching up with the id mainstays during QuakeCon. The Q&A with Willits is an article-format conversation with the id lead programmer covering various aspects of DOOM 3 development, while also touching briefly on Quake IV. Quake IV also comes up in the John Carmack Q&A, as id's lead programmer makes it perfectly clear that their next project will not be another sequel:

John Carmack: Wolfenstein worked out so spectacularly well. Inside id there is a group that really, really does not want to do another sequel. Our next game is not going to be a DOOM, Quake, or Wolfenstein sequel, it's going to be something new and that is a foregone conclusion.

We knew that we were going to license that out and let someone do it.

The work that was done with Wolfenstein, in the end it turned out great, of course, everybody loves it, but it was painful during the development. At one point we had every programmer at id working, trying to stabilize the code base to make things okay for shipping.

But still, we looked at that as a success and we are hoping to replicate that success with Raven doing Quake IV. Raven has always been our lead engine adopter. It was a foregone conclusion that Raven would get the Doom engine early, the only question was what they were going to work on.