CHAPEL HILL, N.C. — Bogus classes and automatic A's and B's are at the heart of a cheating scandal at the University of North Carolina that lasted nearly two decades, encompassing about 3,100 students — nearly half of them athletes. At least nine university employees were fired or under disciplinary review, and the question now becomes what, if anything, the NCAA will do next. Penalties could range from fewer scholarships to vacated wins.