I still have no idea what type of game this is supposed to be. Fallout 3 style open world with vehicles but no levelling or perks?
A 2011 release would mean a very long dev cycle so did iD finalize the feature list a year or so ago and have been making nothing but content since then? It sounds to me like iD still has to make some key design decisions and define scope. Thus they can't say how much (if any) support there will be for things like multiplayer, coop, mods, etc.
FYI - I didn't think Doom 3 was all that great. Tech, not gameplay, seems to be iD's forte. Mods like Last Man Standing are what kept Doom 3 alive for me.