GameInformer sat down with John Carmack and Todd Hollenshead at CES 2007 for an interview. Here's a short quote:
GI: After Enemy Territories: Quake Wars ships with the highly modified Doom 3 engine and the MegaTexture support, is it time for you guys to move on from that engine?
Carmack: Yes, the in-house development project that we’ve been working on is all new technology. It still has some roots in the Doom 3 technology, but almost everything is new in there. We’re still not talking about exactly what the project is, but it’s a new IP, it’s diverting a little bit from the standard id formula and it’s not just a first-person shooter. Technically, it’s build around an advancement over the MegaTexture technology from Quake Wars. Where that was applied just to the terrain, the version of the new technology applies it into everything, so we can have that level of rich detail on all the surfaces on the entire world. That’s the push that we’re making with graphics technology.