Hmm, I wonder what the best way to tell EA that yes, this would be a good game to make would be? Facebook petition perhaps?
Either way, I really hope this happens. Mirror's Edge was a game that I actually dismissed as a JRPG when it first came out and never even looked into it. Fortunately, my mom ended up purchasing it for me for Christmas the next year and I haven't put it down since.
Objectively, it isn't perfect, but when other companies are allowed to release slightly more polished versions of the same game for ten years (Here's looking at you Bungie) or to release games with entirely game-breaking flaws and bugs (Fallout), 'perfection' doesn't appear to be a strong criteria for a good game.
As far as improvements on the game go, I see three major points almost everyone touches on: the guns, the linear gameplay, and the story. these are the points that come up most, so I'll toss my two coppers in the pond.
When it comes to combat, I don't think they should take away the option to use a gun, it presents a hidden moral choice in the gameplay, yes it's easier to grab that machinegun and mow your way through the cops, but it felt wrong, and even on my first playthrough, I found myself preferring to simply evade and outmaneuver my opponents (until I hit the ninja cops, if my city ever gets cops like that, I'm leaving). Perhaps they could explore that a bit, maybe add consequences for choosing the easy way (Like the star rating from GTA, shooting cops will make them call for backup, making later sections even harder?).
Being railroaded along predetermined paths did feel like it cheapened the experience, and some more freedom to pick your path would improve the game greatly. I like the idea some of The Escapists had about opening up the entire city a la GTA and Assassin's Creed, and would give the dev's much more freedom to expand the world and offer depth to why you do what you do through, and I can't even believe I'm suggesting this, side quests and collectables.
As far as story goes, let's face it, it isn't Mass Effect or Dragon Age. But when you get down to the nitty gritty, and Spoilers ahead, be warned, Shepard is an interstellar BAMF who saves the galaxy from an invading race of alien machines and The Warden is saving the world from ugly evil things. What it needs is depth, why is the government 'evil,' what do they do? who is fighting them, what are their motivations, hell, what are Faith's motivations? these are questions that would need to be answered for the story to really shine.
In conclusion, I think Mirror's Edge -needs- a sequel, it is a unique experience and a brand new concept that is literally full to bursting with untapped potential. Do I think that Mirror's Edge 2 will be the next Mass Effect, Bioshock, or Fallout? No, I can wish and dream, and who knows, Dice might pull the rabbit out of the hat and blow our minds, but I think it's got a long way to go before it gets there. On the same note though, I feel that the gaming community on a whole would be worse off if we let this die. If Mirror's Edge gets shuffled to the side to make room for Generic Brown Shooter No.5768, what does that say about the state of our industry?