I wouldn't guarantee championships or even that they will dominate. All I'm saying is that these guys are top notch drivers. It doesn't matter if its NASCAR or soap-box derby - these guys can drive.
I would also add that they both have success on ovals and road courses. Are they superior to the top drivers in NASCAR? Who knows. The short tracks will probably be the biggest learning curve but they have plenty of experience at Michigan, Phoenix, Indy, Infineon and maybe one or two other tracks.
Great drivers are great drivers.