They need to get back to "STOCK" cars, not identical (except engine) jellybean-shaped funny cars.
I'd like to make 'em beef up stock frames or unibodies. And if it's front-wheel-drive, they have to run that, too. Either Detroit and Japan will drastically improve fwd technology, handling and durability, or they'll go back to rwd, a trend that is already spreading (Chrysler 300C, Cadillac CTS).
Rules will have to be tightened every two or three years, as race engineers are so creative at cheatin'.
Right now NASCAR is a corporate billboard series, kind of like wrestling with Fortune 500 advertising support. IROC-style "level playing field" driver-focused series have their place, but I'd like to see "pure stock" oval and road course racing that tells us something about the relative merits of cars we can buy and drive.
Oh yeah, requiring DOT radials in factory-available optional sizes would help too!