If it's the hypercar I'm thinking of, it's target performance is that of LMP1 car. LMP1 cars are consistently 5-10 seconds slower around the tracks where they both compete. Impressive that it can come so close to an F1 but no where near "shaming" an F1. That being said, I find events where LMP cars race much more exciting due to all the different classes being on the same track at the same time. I love seeing the GT cars race even though I don't follow any of the series.
I've been wondering about the Ferrari FXX program though as sort of an in-between - cars using tech banned by F1 and not road legal in pursuit of new performance achievements.
One hypercar I found extremely appealing was the Jaguar CX-75 using a turbine powerplant. Those are banned in every racing series. The potential though is staggering, mating the best of electric motors and potential powerband efficiency. Drool. Sorry.
I love how the shape of that new Jaguar calls back to the XJ220! Japan would be the place to field a series that's crazy without being a circus. I too would love to see an all out series but I wonder the extent that humans will be in the car. F1 cars are already pushing 5-6G's in the corners. Perhaps drone-style racing will be where we see insane race track tech. However that tech might quickly diverge from anything that can be applied to road going cars.