Empire Strikes Back anyone
My point being, you can have the good guys look like they are almost done for (a la DS ending) but in the follow ups (kotor2, return of the jedi) have the LS win out.
The republic looked like it was screwed during the DS ending, but it wasn't nessasarily dead just yet. If nothing else, there was still the strongest jedi on Corusant. I don't think that they ever said that the republic fleet that lost was all the ships the republic had either. It was a "quick strike" to quote Carth, so I doubt they could must everything they had. So the Republic was down, but not out. A very bleak situation, but not hopeless. A la Empire Strikes Back. KOTOR2 could be a kind of return of the jedi...minus the ewoks.