Anything is possible with more money and a bigger price tag but it also depends what kind of car they wanna make/market. The RC-F is suposed be around 4000 pounds and no doubt be more expensive than the Supra. Is just a matter of choosing performance over luxury and every little creature comfort.
The flagship car for Toyota has to have soul in both design and name. The Supra fills that. Something like 2000GT or even FT-1 does not. The word itself should have meaning especially when the brand itself has lost some of its performance luster.
Trademark registrations are not as simple as sitting on a name indefinitely. Car manufacturers let old names lapse all the time and they also renewal trademarks sometimes without necessarily intending to build that vehicle.
I'm not sure when the Supra TM lapsed but a renewal can sometimes mean...