I don't think pulling the contract from Atari/Obsidian is a smart idea (except when Atari is too greedy or not able to to produce the game). With Neverwinter Nights Atari has a pretty strong brand name for D&D PC games and the experience how to build them.
You seem to assuming there's anything to pull, and I'm questioning whether there is. I think this whole "Only Atari can make ALL D&D GAMES 4EVER!" deal that some people seem to convinced is the case is pretty much as delusional as the "Only SOE can make SW MMOs!".
I don't see any evidence, whatsoever, that Atari has "the experience how to build them". Turbine's DDO for Atari was total crap, frankly, on virtually any level (from art design to "being D&D" to "being a good MMORPG"), as reflected by it's subscription figures, and BioWare/Obsidian's NWN series isn't so compelling as to draw people from miles around. Frankly, the D&D name is a whole lot bigger than NWN.
The only other company with that much experience is BioWare who work for EA, but with Mass Effect, KOTOR and Dragon Age they also have their hands full at the moment. Also I don't think that EA will be any less demanding than Atari.
Bethesda might also be possible, but their games focus on single player only and imo the balance between combat and role playing they prefer doesn't fit D&D. Also the quality of their games can be debated.
Another idea would be dtp/Radon Labs, a German company which recently released Drakensang a "The Dark Eye" game similar to Neverwinter Nights, but I don't think that Hasbro/Wotc will license D&D to a German company as the main market for D&D is not in Germany. Also Radon Labs are a small company and very likely not able to handle such a project.
Really, I think you're completely off-track here. There's no reason to believe that a publisher or developer with previous experience building D&D games would help at all in developing a GENUINELY GOOD 4E game. I'd rather see the license go to someone who hasn't put out a lot of previous D&D stuff, and who is less locked into convention.
The Atari name does not sell games, and that's a fact. Of all the names mentioned, only one does. BioWare. And it won't be them, so if it's not BioWare, then it will be someone else, and the only thing that matters is that they are committed to making a good, successful game, and have appropriate funding. Even a brand new studio would have as good a chance of putting out an excellent D&D 4E game, I'd say, as say, Obsidian, or the random German company you mention.