Wave 1 of Prime RID has 3 Sportscars (Cliffjumper, Bumblebee, Wheeljack). Over the course of the next 4 waves, we'll be adding another 4 to those. (Vehicon, Hot Shot, Repaint Bumblebee, Dead End. 5 If Rumble is in there).
Why is it impossible to have 5 dinobots, but ok to have 7 sportscars?
(PS: I am officially sick of sport car Transformers. I want an old junker damnit. Or a mom-mobile Station Wagon.)
Simply, Hasbro has spent considerable capital on building in the public zeitgeist the knowledge of that difference. Bumblebee is, in people's minds, SPECIFICALLY a yellow sports car. The others, while getting less screen time, are still clearly indicated as different characters. Bumblebee is not a Vehicon. That is obvious. Grimlock is not Snarl? Not obvious for the average person. Perhaps after FOC...we'll have to see.
For the past decade, Hasbro has chosen not to maintain that amount of public knowledge for the Dinobots. It's not in their game plan. None of the groups have really gotten that kind of treatment except maybe the Constructicons, and we didn't even get all of them in the movie series except as Legends. That's why Bruticus is a long shot for them. It's riding on the predicted strength of Bruticus as a pop culture icon when FOC hits.
So, yeah, the Dinobots may perhaps get the same treatment if FOC gets really popular. We know there's a Grimlock coming, but he's likely to be the Dinobot stand-in unless there's some clamor for the Dinobots as individuals.