You know what? The more I (re)play, the more I think an ending where they all fail and die would have been more fitting. (spoilers)

I just passed that point in the game where Liara talks to you about the time capsule. It would have been a great ending if Shepard ultimately failed and the Reapers won, but the future race of, say, Pyjaks found a capsule 49,998 years later.

I'm not saying that it should have been the only ending, but it would have been great for a 'bad' ending.

PS: as an aspiring screenwriter and movie director, that scene is one of the best scenes in the ME history. The music, the writing.. I wish it wasn't so short.