Just checked NewEgg and one can still buy OEM
Windows XP, Vista and 7. It would seem that, in order to make this threat legitimate, MS would have to first stop etailers, retailers, etc. (I can also buy these as my local Microcenter) from selling individual media/license kits. Although signs in my local store clearly state that the software kits are "intended" for use on pre-built systems with the OS already installed, it makes no real sense to have open displays of these. To make this work without looking fuzzy, MS would need to yank all of these copies and make them available only through distributors who followed their rules. This would probably mean that a minimum number of licenses would be needed to make a purchase. OEM builders buy in bulk and hobbyists rarely would do that.