I would not be adverse to letting V or AT&T own as much as they can afford to buy as long as they are required to easily share it with competitors at a reasonable cost.
Not sure of the mechanics of this concept, will let the lawyers and technical experts work that out. -- The difference between genius and stupidity is that genius has its limits.
T-mobile is already testing spectrum sharing with government owned bands, AT&T and Verizon hate the idea obviously because it decreases their capability to starve all of their competitors by buying spectrum and sitting on it.
It would be a wonderful thing for wireless competition, but with our current government and regulatory agencies, not to mention the fact that Verizon and AT&T seems to have bought the fcc, it will have a tough time.