"But what happens if many users (highly likely) don't bother buying new hardware and just go down the home upgrade route? Will the large corporate customers go into rolling out upgrades instead of a hardware swap? If they do than MS is really digging a hole here for the OEM's, and they aren't exactly in a strong position as it is. Do think it's going to be interesting though to see how it shakes out down the line."
Easy fix for you: Win 10 will probably not boot on any of the systems running W7 (CPU tweaks, RAM, ...). But surely it'll boot on most default W8 gear. Solved. W7 killed through "no support", and W8 killed through "I want the mistake fixed". Actually quite clever.