Some Facebook group I've joined has a guy 'predicting' the next update will have the following:

Aston Martin V12 Zagato
Bugatti Chiron
Lamborghini Centenário
Pagani Huayra BC

Real Racing's Twitter and Facebook has just put out a picture of the Lamborghini Centenario Roadster. The guy made this guess on the 22nd and RR posted this on the 27th.

Real Racing hardly posts content outside their license or whatever is relevant to the focus of the latest update.

Coincidence/Red Herring? Probably. It also is unnatural for RR to post cars for the next update. I'm still hoping for more GT class racecars or some other motorsport category. Just gotta wait till halfway September then. Apologies for the false alarm to some of you.