Sure, you could buy, install and then sell the disc. But if a potential buyer will be charged another $60, they sure as hell wont pay you $60 for it. So unless the 2nd account fee is way less than the original cost, there is no market. Guess we will have to wait for an official word to see how it plays out.
I for one, think its a great idea. Some developers/publishers work very hard and should be compensated for their work. 2nd hand games have been a sticking point for many years and I applaud MS for finally addressing it.