I doubt they'll let us become a Jarl. I don't see the point really. What would we gain from it? If they DO add that, I hope it's not a requirement to rebuild Winterhold. I like the Imperial Jarl for the Hold, and I have no interest in being cooped up in that miserable snow-ridden wasteland in the first place. That's why I let Tolfdir handle the day to day business of the College in the first place.
Rebuilding Winterhold would be nice though, and it'd also be nice to do something to improve the College's PR (or make it worse, if that's your interest). Though I doubt we'll be able to make it a thriving school. It already doesn't have enough room or faculty to have a respectable sized student body.
what makes me think it's allow you to become Jarl is firstly because many posters on the forum have been asking for it and secondly due to what the Jarl of Falkreath says to you.
He says something like how easy it is as the steward does all the important stuff and that you should try it one day.
I guess the old Jarl would become your steward so it'll still be the old team of Winterhold running as you'll be off exploring Skyrim most the time. The big difference is through your input Winterhold will be more than just a couple of wooden shacks, a longhouse and an inn