I wouldn't mind seeing the Torians getting ground into green paste, but I don't think that's what's going to happen. The Torian, Drath and Iconians already have their past difficulties that they have suffered through and have conquered or at least are now freed of. If say the Iconians were simply wiped out after being rescued, it wouldn't make for much of a story. If the Torians after freeing themselves from the Drengin aren't able to forge a future for themselves but instead just get stomped, it would be sad. (funny, but sad)
I think the Drengin have too much of a major role as the main antagonists / instigators of this conflict so they are too involved and valuable for the story to disappear completely.
The Yor have a novelty being the only race of artifical life forms, so I think they have a free pass.
The Terrans won't be wiped out, I don't think I have to explain why I don't think so there.
The Altarians have the 'we look human' mystery to be solved, and are one side of a major conflict with the Drath / Korx so I don't think they'll be exiting either. I wouldn't mind if Netro Mancer bit the big one though.
The Arceans, I think, have more character than the Korx and they are certainly a strong race, but that might just make them a target. They're actions definately deserve some blow back and will probably take a big hit at least if not be exterminated. Though being one of the oldest of the new race, and a strong militaristic civ, I tihnk they probably will survive.
Personally, I think it should be the Korx. Sure it's hard to get rid of people like that because opportunists tend to be survivors however, they can survive without being a major independant civ. I think that being used as tools for the Drath though leaves them with a fairly minor role in this galactic soap opera and I can easily see their decisions ending in disaster.
Just FYI, I haven't finished the single player campaign, so I could be missing some vital info, but those are my thoughts.