As far as a new stadium goes it is more of a when not if it moves downtown. I agree with a 10 to 20 year estimate leaning closer to 20.
I know many believe the Toys r Us parking lot is the best place for it and others believe the mall parking across from the bay or in the north downtown area. Sadly you are all wrong, the best place for it is where the Sturdy Stone building is. kill 2 birds... litterly kill that building. (I am only kidding about you being wrong
those are all excellent locations I am fond of the lot across from. the Bay myself) jokes aside it might actually work with the BRT system using 3rd as a hub and being the most centralized downtown location and a fair bit of parking around. But would be far to expensive unless it is demolished and the city can get the empty lot cheap for some reason. A person can dream right?