It was and still is a very cool concept. My only concern is that with 1) the number of parts to build a single car and 2) the number of parts to support its numerous configurations, the cost is going to be way too high for you to make even a few cars. And belt drive... materials selection is going to be crucial for the belt, the standard timing belts intended for small machines and 1/10 TC's just aren't going to wrap around tiny pulleys. Either that or you could go the TGR way with a non-tooth belt (you could even use a 3mm wide rubber band) but then the drivetrain wouldn't be very free.
Suspension-wise, I love the concept but I fear that in 1/28, unwanted friction will hurt its effectiveness. If I had full reign over the design I might even try out a deDion tube suspension for its almost frictionless action (and then use a tunable damper in conjunction with it).
Your car though, I just wanna see something cool come out of your 7-year project.