I think migration to PC3 from GTS and Forza would be a lot higher if there were a lot more low power roadcars in the Road classes.
They are pretty low in numbers, and wildly different in pace, so damn near unusable for racing unless a one make.
6 cars in Road G, varying from a 120hp Escort to a 440hp F-150! How can you race those? You basically pick the Mustang or the F150, or struggle at the back.
4 cars in Road F (3 if you didn't get the Civic DLC) from 256hp-306hp.
8 cars in Road E (7 if no Porsche DLC) from 340hp-525hp and some of these can be handfuls on the stock tires.
6 cars in Road E, and we are starting to get into some even trickier cars to control..!
PC2's massive increase in difficulty of control over GTS/F7 might not be so daunting if there were a better balanced choice of low power road cars, and more to do with them. I find handling pretty easy even without a custom tune at the low end, enough that, if GTS/F7 migrants were locked out of the higher classes until at least a basic starter series in Road G class cars, they might not run back to the arcade games so quickly. Initial impressions matter a lot, and PC2 doesn't help itself out much allowing noobs access to all kinds of high power racecars that are quite drivable in arcade games but incredibly tough to control in a sim.
Keep them fully engaged and occupied driving a nice selection of low power cars together, let them slowly adapt to the increased skill needed to get up into the higher power cars, and let them do what they used to in GT6 etc., have fun driving low power road cars around without losing it all the time, and PC2's massively better track selection and time of day progression might make more converts than we are getting right now.
Hell, give them stickier tires (at this 'Beginner Level' only), soft slicks, whatever... The main thing is, keep them playing! PC2 will hook them, and hold them, and get them to persevere up the ladder. But allowing them to jump into a Formula car or a Can-Am or a Vintage F1 the day they try the game, and give them little selection at a level they CAN handle, it's a recipe for making sure they don't stay...
On paper, PC2 should be killing GTS/F7. But it's not. If PC3 wants a bigger slice of the GTS/F7 pie, they need to smooth the introductory path for those drivers.