Well, whether it's possible or not, I don't think MP- style loading would work with TC - it worked in MP because every single room was separated from every other by doors, and the game could load whatever door you opened. You can't do that in a city - you are able to see in all directions. They could do some kind of technique where it loads it as you go, but it wouldn't work like MP's.
Anyway, the game sounds awesome. I'm glad that this time you get to be a cop instead of a criminal. I mean, GTA3 sounded like an awesome game, but the idea of killing random people and slaughtering cops doesn't appeal to me. I just want the huge, open environments with lots of stuff to do. I really hope this game doesn't go with the extreme... "mature" theme of GTA.
Yet I wonder if it won't fall prey to Morrowind syndrome - I mean, with an environment that huge, will they really be able to come up with enough content to make it interesting wherever you go? (keep in mind, I like Morrowind, I just wish it was more compact).