Maybe a new concept where a few of the original concepts return but capacity limits and actual road cars are involved. Allow the turbo cars again, hybrid and pure electric to each run in their relative classes with a limited number per class.
The lead up races could be for each class to determine who was "King of the mountain" etc to get the field for that class with grid position based on the actual individual car's best lap shoot out style.
Remember when the Mini Cooper ruled the mountain? The Cortina's, 6 cyl Torana's ..... Those were great races too, they don't need multi million dollar purpose build race cars with super high tech V8 engines to attract a crowd, they just need to make it a competition the fans can relate to if they want the crowds to follow the racing with the passion of old ......
Just trying to picture a Prius at full squirt doing laps around Bathurst ... just can't seem to get it into focus

T1 Terry