Harry Brighouse writes such interesting stuff. You should really surf over to Crooked Timber and read his marvelous comments on school chocie–Trading Places. The post discusses tradeable rights to admit highly qualified students, but I was thrilled when I followed the link to an earlier post, Lotteries in Admissions to Academies, which has a fascinating anecdote on the "feasibility" objection. I’ve written about this elsewhere.
If I might get up on my hobby horse once again, "feasibility" is just like any other argument: it must be made clearly, backed with evidence, and applied consistently. It is simply bad argumentation to hand wave and say, "That will never happen." What do you mean by that? What are your criteria for feasibility? What evidence do you have that the criteria will not be satisfied? Are you willing to apply the same criteria to your own positive suggestions?