Theta_Sigma: Exactly, but fan backlash not withstanding, and even with a talented actress in the role; it would take a great amount of effort and push for fans (or at least the vast majority) to accept such a dramatic change. And, as you've said, it could be looked upon poorly/misinterpreted which could cause a lot of problems amongst many fans. Sometimes the risk is not worth the reward.
I would love to see Susan come back, and it would make for an interesting dynamic between her and a current Doctors. As much as regeneration is a part of Time Lord physiology, they could write some minor animosity between the two as the First was the only Doctor she ever known and could show some sorrow over his incarnation being long gone, but also conflicted with knowing that it's still her grandfather. That could lead to some awesome character development, in my opinion.
Seeing Jenny make a return would be nice too, since for all intents and purposes she IS a Time Lady and it could lead to her wanting to learn more of her heritage. Which could lead to the next thing, the return of the Time Lords, I agree a great many stories dealt with others of his species and there is so much which can be done. Like the imprisoning of Rassilon as part of them trying to make amends for their transgressions with the Time War. This could also lead to Rassilon taking a more ominous and even Black Guardian-ish type looming threat. I have a tonne of ideas in my head of things I'd love to see them try. So much potential that they can explore.
Many of my thoughts exactly! :D Another thing with Susan that could be brought up are her parents. Where are they? The Doctor obviously had a son/daughter, what happend there that resulted in him leaving Gallifrey with her?
One thing I want to see if they start brining back the Time Lords is the Valeyard. Been fascinated with that character since his introduction, and want more. I'm wondering if John Hurt's Doctor is a lead in to the Valeyard, but I got the feeling that he's a past incarnation. Going to keep hoping for the return of the Valeyard.