R8 GT3 is highly unlikely because no one is racing it in Japanese Super GT. The car should be done by Revell Germany, because they have Audi license, and the races take place mainly in Europe which is Revell Germany's home market. I like the fact that they released recent F1 and DTM cars, so they aren't dormant like Tamiya, but I'd like to see Revell Germany releasing two or three brand-new Nurburgring and Le Man subjects.
After the Z4 in Jan 2012, the next logical choice for Fujimi will be F430 GTC for Ikamusume tie-in, and maybe 458 GTC simply because it's a Ferrari, though I don't keep my hope high on those.
Ebbro has an exclusive license to Super GT diecasts, so they are familiar with the subjects. But knowing what the company founder couldn't do during his days at Tamiya, their first closed wheel subject in 1/24 scale will be Porsche 962, but that's just my wishful wild guess.