Actually, I think it would be a pretty smart move for Sony and Microsoft to block used games.
Maybe from a pure business side of things.. these aremeasures that usually would only come to mind by an economy major who's purely looking at the numbers and trying to improve them but forgets the bigger picture and the oddities of the branch they are working in.
Imagine a car manufactures who binds your new car to your ID card or something like that.. the whole car market would tank (not really comparable to video games i know).
I'd bet that most gamers would suck it up and deal with it over time.
And this is why Sony and maybe MS are even thinking about it however companies might miscalculate the gaming community (as Sony has proven with the release of the PS3).
If both of them block used games by whatever means then gamers would have no choice. If even one doesn't it might be the deciding factor in the next generation console wars given that technology wise both consoles are closer in capability and so it's once again down to taste and preference.
If (and it's a very likely if) Sony announces the PS4 on the 20th and rumors are true that they'll block used games MS has the chance to evaluate this move for a few months and decide what they will do.