of the extra features you mentioned the onlything interestiong for most new buyers is the wireless, and for most people it won't matter if its n or aan older g wlan since they don't have internet connections fast enough that this makes a difference.
ps3 slim also mainly boosted sales cause it pushed the ps3 price into a lower price region which opened up new customers. for the new xbox thats not the case so i don't think it will do much after an intial bum from those peopels taht want to replace tehir old 360.