The journalist is a genius (not):
" A free upgrade for all would make sense, though, in that it would make it easier for Microsoft to entice as many of its users as possible to upgrade to the latest and greatest."
Stupid circular logic every way you look at it.
The only way I would see it being for pre Win 8 machines is if MS took a view they would be making money out of their metro app store and they feel they won't be making money out of OEM hardware any more. Unlikely but you never know...