First, I don’t intend this as self-promotion. Over at KartRank.com we have data on kart counts for pretty much every track in the Eastern US, and for Midwest tracks we have data going back to 2011. If anyone would like some specific data I’d be happy to provide it.
In general my take is: Cadet Sportsman is dead (really just a Man Cup class), Komet classes of all varieties are basically dead, Yamaha is just kind of maintaining. Clone seems to have turned a definite corner and is on the way down, with almost every track except some in the SE switching to 206 or running a combined class. 206 is really exploding this year. At the national level Pro Gas seems to be the only game in town for 4 strokes, not sure why Gold Cup even bothers with the rest. Events like RIGP have very strong 206 counts, so I think it can work for big races.
TaG is fracturing, seems like every manufacturer wants to be like Rotax and have their own series, with lots of Leopord/Parilla only and now Rok Cup. I’m guessing this can’t be good long term.
Canada might have the right idea with the Rotax/206 combo.