Part two of Thresh's Firingsquad's John Carmack Interview is online, with more Q&A with id Software's lead programmer about the gaming industry, the possibility of self-publishing, what happened to Trinity, loads about the future, and a bit about his favorite genre, the first-person shooter. This means that id's next title will be another shooter, right? Well, maybe, but maybe not, according to this answer:

It's very likely to still be a first person game, but it may not be an action game. Graeme and I have been sitting around talking about game design ideas for different things, and they cover a pretty fair range, exploring a few different choices that we've got, but we're not prepared to talk about any of them yet. They are likely to be first person, almost certainly.