For those that don't know quite a few games recently have been released with a code that you have to enter in order to play. (Kind of like CD-Keys) If you buy used you get very limited features and if you want all the features you have to pay $10. So assuming they go with something similar it won't actually kill used game sales, it just means that you won't actually be saving any money unless GameStop/EB/etc sell their used games for cheaper than they do now. If they don't sell their used games cheaper then you aren't saving any money by buying used and it makes buying new more appealing.
what games are these ? i play a lot of games and have not come across any of these and have 2 buddies that are managers at gamestop and i have not seen this
if you talking about the code for the extra goodies ? then WHY should a used copy be allowed to get the goodies ... imho they shouldn't