There will never be another Supra in the Toyota line, PERIOD...
Toyota has adopted a mainstream style of thinking when it comes to design and marketing of its vehicles. They are not looking to produce "Niche" or "Flagship" vehicles but rather conservative, highly marketable, eco-friendly, vehicles.
I too wouldn't mind seeing a new Supra hit the market. But like it has already been said, if it isn't a Turbo I6, it isn't a SUPRA...