The following is based on the limited information I've been given. I could be quite wrong in some details, but am pretty sure the basic idea is right. So...
I just want to point out, if it hasn't been said yet, that Atari is connected to Infogrames, which is owned by Hasbro, which also owns Wizards of the Coast. This means that Atari has recieved all rights in producting all D&D games.
IF Atari goes bust, then the licence would just go back to Infogrames.
And I'm sure NWN2 will be released before Atari could go bust anyway. The main worry I'd be having is how much support there will be after the game launches. If the funding disapears from Atari to Obsidian, then I'm not sure who'd be paying for any unreleased material (patches, features like the DM client, and the like).