Well honestly I hope (wish?) that the group C cars will be moved to a Gr.C category, leave Gr.1 for LMP1s and VGTs. A new category can be created for EVs called Gr.E, and that a Gr.5 will be created for the roadster TC as well as the Prius TC and Honda CR-Z TC if they (rightfully) get brought back.
I can't agree, except for the idea of a group for EVs, though I'd create an "NE-Series" instead, as I don't think anybody would want to face a Tesla Model S or a Porsche Taycan using a BMW i3.
I think the major groups should have continue to have relatively uniform power/weight, which you can especially see with Gr.3 and Gr.4. The touring cars/RM cars from the PS3 era do not conform to a certain set of figures like Gr.3/Gr.4 do, but instead, they just have more power/less weight than the stock version. I think they should instead be treated as tuners that go into the N-Series like they are in GT Sport, but I do like the idea of there being some sort of Gr.5 for lightly-modified cars, as long as they have relatively uniform power and weight.
As for Gr.1, I think Group C cars should stay, as I think the calls for the Group C cars to be segregated are the result of most races (Gr.1 or not) allowing all cars within a class. I'd say that instead, we should simply hope for the majority of races being those that only permit a certain group of cars within a class, like that Gr.1 race at Fuji that only permitted the Group C cars.
I especially advocate Group C cars staying in Gr.1 because I'd actually like to see Gr.1 in the Manufacturers Series - or at least expanding it beyond Gr.3 and Gr.4 - as I think a large amount of automakers could be represented, between LMPs, VGTs, Group C cars, and other prototypes like LMP2 and DPi cars, or WSC. That said, for something like the Nations Cup or a daily race, I'd seldom permit every car from a class to enter at once, and instead, the overwhelming majority of races would involve a sub-set of cars, perhaps modeled on a campaign event, whether it's a campaign event returning from a prior game in GT7 such as Boxer Spirit, or a new one that gets its genesis in GT7.