The bulk of the promoters money will come from TV, the TV will make their money from subscription and advertising. The circuit will pay the promoters as well, they make their money from advertising and gate receipts.

Also each individual team and rider will have their own sponsorship deals in place.

Its a fairly big pie but there are lots of slices to go around, the riders and teams would earn on their results as well as providing full time employment to their guys and gals.

And ultimately we, the public who want to be entertained, will have to watch and/or attend in big numbers to make it cost effective for the advertisers and sponsors.

But this happens right now with loads of motorsport race series, both worldwide and domestic, lots of different categories of car racing, etc. are a  "travelling circus". Although that term takes away the fact that this would be an exciting series of road racing by the best riders and biggest teams, it would bring in money and new teams, riders etc.