I don't think the number of championships is the problem. Right now we have less F3 championships then there were some years ago and the same applies for FR2.0 level. Remember how there were French, Italian, Swiss, German and I think even Swedish FR2.0. Even one year Formula Master had Italian championship and Euro 3000 had Italian championship for many years.
Problem is the $. If they ask for less, naturally there will be more drivers! This is the easiest way to widen your potential market, right now it is Lamborghini Aventador super car or more territory
Go down to Porsche territory and you can have several times bigger market size.
Anyways, I have a question for those with many, many years in the sport. How many people do you think were involved in motor racing back in the 70s-80s compared to now? I ask excluding these involved in F1.