There's tons of people from fairly modest backgrounds in the legal profession, including ones who went to elite law schools. (E.g. Lawrence, Kansas, of all places, is the hometown of not one but two prominent south asian lawyers, Kannon Shanmugam and Judge Sri Srinivasan.) That's the direct result of the LSAT democratizing the legal profession over the last couple of generations.

I suspect you're correct, though, that if Harvard closes those doors, talented people will go to the University of Iowa (my wife's alma mater) and do fine.