There are no used games in the pc market. The smart publishers just start slashing prices after a while. And steam sales. Those damn steam sales!
I'm saying that the used game part isn't the damning thing, here. It's the always online, which MS will spin to be a good thing, will end them. The first time their servers bite the dust or are down for maintenance or whatever, then the real backlash will begin.
I'm not looking forward to that day, as all of gaf will be united in a giant game of "I told you so."