Do you honestly think that retail outlets will even consider selling computers without those stickers?
That's a tough question. At first we all assume that the stickers must be pretty important, but my guess (pre-looking-at-evidence) is that most retail sellers would in fact be willing to do just that, since users never asked for those stickers in the first place; they're ads.
I wouldn't be so sure about that. When Windows 8 comes out 'Windows 8 certified' will be all over the adverts and retailers such as PC World and Comet will be expected to say things like "this computer is better than that one because it is Windows 8 certified".