I've said it a billion times. GT is only meant to move Playstations. There is already two subscription services on PS. PS Plus and PS Now. It's more likely GT will be killed.
Actually, if you think about it from the perspective of GT getting the axe, it all makes sense.
(conjecture warning. Keep your pants on)
The PS4 is doing just fine. GT is not needed like it once was. The bulk of what we will get in content will be remade stuff because the licenses are already done. It also takes a long time to model a new car from scratch, but updating the GT5/6 cars won't take nearly the same amount of time. The tessellation feature of GT6 meant the 3D model was pretty high poly to start with. There's new shaders and textures on the cars now, and some detail changes, but they are not completely new models. That's just unnecessary from a modelling stand point.
There's fewer features because that means less testing. Makes sense when you are trying to keep the cost down.
If you go through all the (high poly) cars that were in GT5/6, and list the ones we are missing, divide those into packs of 11 cars, and that's going to be the car content we get fro here on out for the next year. For each 11 car pack, there will be 1 car that is all new (model wise). Every other pack will get a car that is new to the series, while the other gets one of the classics from the standard catalog.
We'll probably get the M3, Nismo GTR-LM, NSX Type zero, FTO, and one more.
I wouldn't be surprised if this is the last GT ever. Servers will run until the PS4 kicks the bucket.