I'd love a release of the trilogy on the new gen consoles, if nothing else just so that I can play through again (360 went down a while back.) What we will most likely get, as people have stated already is a graphical update, though to what extent is what I would be interested in finding out. Also give some other examples I would say we will get most if not all DLC, along with all three games on one disc. Finally, no more switching discs all the time. I honestly would expect them to include the small stuff too, like weapons, alternate outfits, and even Pinnacle Station. Why not? The more content the better right. Multiplayer updated for current consoles would be great, but honestly I think that would take more work than they want to put in, but it could happen.
As for people thinking that a remaster is going to mean anything in the way of new story content, that's pretty much just a pipe dream. The only game that I can think of that got new features when it was moved to a new console is GTA:V. And, I hate to say it, but ME will never be Grand Theft Auto. Not saying that game is better in any way, though you can make that argument if you wish, a game being good or bad is mostly opinion. but even then I'm pretty sure that they didn't touch the story, and that's what all the ending haters want, a new ending. Not going to happen, sorry. For a million reasons, it just won't.
Personally my best case scenario would be the above mentioned improvements, and maybe, just maybe a few tweaks and extra finishing touches on ME:1. Just my personal preference so don't judge, but I think the first game would benefit greatly from a little more variety where weapons and armor are concerned. Also the combat from the third game is just more enjoyable, for me. The enemy AI, cover mechanics, and side mission level design just didn't make combat any fun. The main story missions for the most part weren't all that bad, but I still would love it if they took a few things from the other two games and applied them to the combat system in ME:1.
But, what I really want is the next full game. A remaster would just be a way of holding me over until the next one is announced/released.