ID abandoned decent single player games after Doom2. I mean, Quakes 1 and 2 were ok, but though they were a quantum leap in graphics, and in player handling (the way you controlled your character and the feedback you got - ID's main strength. I'm not explaining this very well am I?). I got Quake and Terra Nova around the same time and found that Terra Nova was a much better, and more revolutionary game, than Quake. But no-one bought Terra Nova. Once I finished Quake I only played Multiplayer. It was uninstalled a loooong time ago, but TN is still sitting on my HDD.
The problem with ID is that almost everyone (bar Carmack) who was involved in Dooms 1 and 2 has left the firm. Will ID be able to produce a game with the same tension, the same feeling of absolute bloody terror, with a new team?

Plus, this stuff from Carmack worries me a touch. What made Doom good was the sheer number of monsters chasing after you, not the graphics, which were designed to run fast, not look great. It seems like he wants to put loads of eye candy in rather than concentrate on making it a playable game. Give us tons of monsters, Carmack, and make them chase us! And each other! And give us the super shotgun!