Yes, but what if Shepard fails? (I guarantee that will be a possible outcome in ME3). Is the universe just going to curl up and die? Do they have a plan B?

I can tell I enjoy a game when I want to know more about the universe. I love the games but I think they could go even more in depth with the fiction. If not in ME3 I hope theres at least a spin off that answers hanging sub-plots, i.e. driving the geth from Tali's homeworld.

Well they probably have a plan B but since Shepard "can't" lose they just don't tell us, the players. It's like saying what would've happened to Gotham City when Batman dies? Or what would've happened to whole world if Snake failed to complete his mission in Metal Gear Solid 4. Considering Mass Effect's multiple endings it'll be there I'm pretty sure. But the main plot will and always should follow the heroic acts that main character does to save the galaxy. Otherwise no one would've played or at least enjoyed the game. Think about it; you are doing everything right and then bam, while you are very close to finish the job you are dying. No one would want to see that scenario as primary plot. So most likely what you are trying to say is either will come as a DLC (just like The Dark Side missions DLC for The Force Unleashed in which Starkiller becomes the new Dark Lord) or they're just gonna tell it as an uncannoncial side story.

Edit: BTW if you want to learn about at least some of the sub-plots, read the two published books and short comic book series. And since they promised us to fill the empty spot between Mass Effect 2 and 3 with DLC, I'm pretty sure we will see some of those things getting handled. For instance we're gonna learn what happened between Liara and Shadow Broker in the upcoming DLC. And I'm really pumped to learn the identity of Shadow Broker.

most anticipated game asides from tes 5.

Liam lol I can't stand that dude.

it's like bitch but your shirt back on, your not blue or spikey get away from me

Not only glorious jank, but the idea that the story can completely change depending on what you do, or say, or side with, makes it one of the most forward thinking games ever. The amount of story permutation is the equivalent of a Hitman level but in Story Form. And it wasn't just that the story changed, no, it was that you met completely new characters, or missed them, depending on your choices. Made Mass Effect feel static in comparison.

Alpha Protocol was absolutely glorious, indeed. And it was, and still is, more Next Gen than most anything out there these days. In this regard at least.

Pity.