A great bid by Detroit would be what was needed for them to get the Olympics. If Detroit can pull off a great bid for them, they get them. Yes, Mexico City did win, but it could be beaten.
As far as whether it would be different, it most definitely would be. Mexico City is at 7300 feet of elevation, which is over a mile above Detroit. After the 1967 riots, it would certainly be a big benefit to the city, and I think that it might be the catalyst to stop some of the white flight that hit Detroit harder than just about anywhere else.