I feel very comfortable predicting PD are never going to make a primarily racing car/motorsports-focused Gran Turismo game again, GT Sport 2 or otherwise.
There's too many road car models in the game now that they won't throw away, too many manufacturers who they have rebuilt good relationships with and who like the exposure their road cars have in the game. Plus the memory of all the mediocre reviews of launch GT Sport saying "this isn't really Gran Turismo, where's the road cars and progression" - and both SIE and PD historically care a lot about review scores. Then you add MFGT being road car-exclusive as well, and I just don't think keeping up with the modern racing car treadmill is what they want the series to do.
If simulation of modern racing series is what you're looking for, I just don't think this is going to be the series for you going forward to be honest.
I don't think so.
Firstly, the sport mode — the apple of PD's eye — is mostly built on the racing car stereotype. It is because of the sport mode that PD created four categories of racing cars (Gr.1 — Gr.4).
According to PD-Yamauchi, historically, it have always liked racing cars, to the point of even resorting to fictional models. What is the rational basis for believing that the PD would be abandoning the racing cars? I see exactly the opposite of your speculation.
PD is increasingly dedicated to GT racing cars, to the point of creating this revolutionary game design that debuted in GT Sport. But you ask me: then why didn't PD launch an important number of new racing cars for GT7?
I would say that, firstly, from a utilitarian point of view, it is not necessary. There are enough and varied cars to promote the championships. And secondly, from a marketing point of view, new cars (such as some LMh and new GT3 cars) are being stocked to serve as an attraction and one of the reasons to buy GT Sport 2 or GT8.
The GT franchise has always worked in two ways — street cars and race cars. But in the last decade, PD has dedicated more to racing car game design. The GT World Series championships, for example, are 80% held with racing cars.
I would prefer PD to launch GT8. But wishful thinking aside, I suspect PD is working on GT Sport 2 because of the scarcity of modern race cars in the GT7 updates. I suspect PD is saving these cars for a new game, just like it did with GT Sport when it released several debut and original race cars, Gr.3 and Gr.4 models especially.