BioWare games tend to do that. I had the same thing with Dragon Age: Origins and Dragon Age 2. And Mass Effect, of course. :P
Even Jade Empire did the same to me. I was crying in happiness when your Spirit Monk gets resurrected at the shrine and you're reunited with your crew, especially the one you've had feelings for. Sky <3
I am attached to characters on Dragon Age-games too, but it's not in the same level as Mass Effect. I cried and shouted at my TV when I played Dragon Age 2 when that bastard psycho kills your mother. But it's still not the same level as with ME-universe and characters. I mean you got almost the same characters going through it all with you in three games, you're bound to bond a bit with them.
Mini game like the planet scanning: remembering where you put all those time capsules and recovering them!
I dunno, I honestly don't think they'd bring back any of the original trilogy's characters for ME4, except as maybe a minor supporting role (like you meet Liara and maybe do an assignment for her or something). If anything I think they'd want to introduce an entirely new main cast to focus on. The problem with bringing any of the original characters back is that Liara's really the only viable option unless they do a game based like 5-10 years in the past or future, which would seem a bit odd. If you go any more than that most of the characters would be dead. Samara might still be alive, but she's nearing the end of her life as well. The rest of them all have much, much shorter lifespans than asari. I suppose Javik would be a viable option too if they chose to do a prequel in the previous cycle during that time period, or Samara during a prequel taking place in her younger days, but that's still only three. The amount of rage from fans of the other characters would be palpable.
Holy crap, I'm about to head to earth for the final show-down and I just went in to the main battery thinking of Garrus...and Tali is there for the same reason. It's particularly poingant as Garrus bought it carrying out a tech-related mission on the Collector gate because I was scared of risking and losing Tali.
Obviously I have no idea what they'll do, but I think they'd me more likely to make her the narrator of the opening sequence and a mentor figure for the new hero (if they do another hero-centric story) or someone you have to find through the story. Or hell, maybe even have an Asari be the main character and she was your ancestor. Could work if the future is on that end planet we saw with the grandpa and kid.
I personally want to start as the fourth human spectre, promoted by actions in retaking Earth, in a warntorn and shattered galaxy, which is bound to attract some powerhungry and greedy people.
Fourth you say?
-Shepard
-Ashely/Kaidan
-Major Coats
-Player
Who needs a new character?
The alliance steals Cerberus's technology and rebuilds Shepard . . . again.
Though if Shepard chose to control the Reapers, finding a body to work with might be problematic
Putin khuliyo
I really liked that part too. I played through all of the origins...but couldn't get through the rest more than a couple times. I think the only reason they could do that was because everything else was the same pretty much and it wasn't nearly as...personal as Mass Effect. If they were gonna have the same sort of experience as they did the last three games I doubt they could vary it so much with multiple origins. But hey, I might be wrong and frankly, I'd love to be. That'd be wicked.