There will be no Super GT series in GT Sport because of the FIA involvement and the class categories that we already know about for GT Sport. I even doubt there will be any other class than the ones we already know about. I'm sure the closest class will be Gr. 3. This class is a fictional class made up of cars based on real life GT3 cars and fictional cars made according to the GT3 rules, at least that is what PD claim. Anyone who knows about GT3 knows that is kind of funny because there are not a lot of rules that manufacturers are locked into for GT3. The way GT3 works is a manufacturer can build a car that must be available for purchase and then apply for inclusion in the series, then the performance of this car is balanced by FIA so no car is able to dominate the series. But for that reason fictional GT3 cars are probably the most realistic fictional racing cars especially when FIA are involved in the game considering other than being based on a production car and having a ball park weight and power and being a RWD class only manufacturers can build pretty much what they want and Fia will just restrict it so that it is balanced with the other cars. This is the perfect GT class for a game and the best part is all those dream GT cars that can be added to the series.
The classes announced are all great except for rally but I'm sure it has fans. Gr. 1 can be so much better than real life Prototype classes. Gr. 3. is based on what I think is the best race category ever and I'd still be happy if this was the only class. Gr. 4. will probably be the most fun class and it wouldn't be Gran Turismo without N. class.