Alright, the character will be modern suited, and it is not any real character in particular: just a generic program. However, it is interesting to note that he has the same circuitry as Sam, however he obviously is not Sam. Here is a teaser trailer, where you can see him use what looks like a disc/sword combo against unknown enemy characters that bear a striking resemblance to enemy programs from Tron 2.0
www.ign.com/videos/2011/05/26/disney-universe-gameplay-trailer?objectid=109467

This doesn't look like an ad for a fighter game at all. If anything it looks like an MMO, same goes for the title.

And as such, you probably start out with a character who has generic clothes, and as you do quests you earn accessories that you can upgrade your avatar with, like the TRON gear.

Its Tron's costume from Tron Legacy. Its the costume from when Tron breaks free of CLU's control and falls into the water when his yellow lights go to blue lights. Not Sam Flynn's circuitry but Tron's Circuitry.