For the better part of 30 years, I was a Board dir for one of the larger sprint tracks in the upper midwest, my kids have also spent some time in dirt ovals. Alot can, and should be learned from the past and what has changed.
The problem with the Rotax / Briggs LO type of thinking is that is what has eliminated most of the aftermarket that has supported this sport
Pick up a WKA manual from the prime years of Daytona, Dirt, it had 75 major sponsors for that series alone. at that time it was roughly $1500. to be a sponsor. With the entry numbers and the sponsors, at that time all of karting was subsadised to some degree by dirt.
The sponsor thing goes far beyond the big races, every engine builder I have met, parts suppliers all over all work with their local track.
Badger is well known for all the show and promotion we do, still out largest source of new racers come from the shops that bring in their new customers to our track. The shops are the foot soldiers that keep us going.
The problem with the all spec world is, you only have what they offer you, the rest of the world is froze out, you never see their help, or their money.
If you limit the 125 Liquid engine world to one brand, do you think all other brands are just going to give up and go away? OR. are they each going after another series, or create one of their own. Thats why we have what we have now.
Learn from the dirt oval world. At one time it was the largest form of karting,and it made out very well. then it went the spec route, cloans, different forms of cloans everywhere you went. LO206, Hondas, WKA even offered a Suburu class Their all spec, no support for any of them and theres so many none are really strong.