Hardcore gamers paying attention to gaming sites and blogs are a large number with a loud voice but a pretty minor part of the install base. I also think it'll sell well initially anyway, but who knows if it'll have legs. Developers likely love the idea of no used games without more money coming in so I think initial support from the big dev houses will be strong. User adoption will make or break it long term.
Playing in favor of Publishers who fear piracy and used games may work in MS's favor big time. They already have the advantage (given to them by Sony's big blunder with the PS3) of a massive loyal audience of COD, BF, Halo, Madden, Activision, and EA sports fans who will have no idea going into the next Xbox.