I don't think MS want to have a BR because it will be a slap in the face and go against what they have been saying as Starcraft has pointed out- DD (i think that's what he said, if not, I'm sorry).
However, most gamers I know are totally against it since they rather own the physical product then just have something in a HDD that you can't even take to your mates house or swap games with.
Saying this, it is not unlikely since MS will love the idea that everyone will be forced to buy a game, sharing games with friends will not be possible and it will kill of the 2nd hand gaming market as we know.
However, if this is to happen and the PS3 offers games to be sold in physical form as well as Ninty, MS will end up shooting themselves in the face (not the foot) IMO.