Seamer mentioned they'll sit down with manufacturers to gather their input on the series. How the cars will be moving forward. COTF should have been that time to sit down and ask manufacturers what they think. Rather than say, you can run your body shape, BUT you need four doors and a V8. Then, we got, okay, you can now run your 2-door coupe, 4 sedan and sedan with a hatch, turbo or NA or whatever engine configuration. Again, it must fit the roll cage.
DTM and SuperGT and as Seamer mentioned, NASCAR have these round table discussions. SuperGT made it a must that the big three all remain in the series. Here's the perfect example
https://au.motorsport.com/supergt/news/honda-nsx-mid-engine-2020/4325129/