I have bought every GT game since GT3. I pre-ordered GT5 and bought GT6 within it's first week. The thing that should worry PD is that someone like me, who, though critical of the many flaws of their last two games, has supported them and bought and enjoyed all of their games since PS2 (used to hire out/borrow the PS1 titles), is not planning to buy GTS. I may pick it up second hand once everyone returns it lol, but no way will I pay full price for it.
The worrying thing is, I'm in no way excited for GTS. It's utterly underwhelming at this stage, and I say that as a massive car nut, a massive racing fan, and a massive racing game fan. I've got 8 racing games on PS4. I'm very excited about AC on consoles, and plan on buying it soon after release if it doesn't turn out to have huge Pcars style issues (I doubt it will, but anything's possible), and after seeing the details of F1 2016, I am definnitely getting that, as it looks and sounds amazing, a big step up for the series. But when I read all the details about GTS, I was bummed out. I can see I'm by far not the only one who feels this way.