It will be interesting to see what happens when the law minded guys get moving. With many computers these days, there is a "restore to factory" option - Dell for example.. The buyer has paid hard cash for a computer with, say Windows 8.1 installed. he is subjected to the MS bombardment to upgrade, and succumbs... For several reasons, a year could go buy before that user discovers that some items are not satisfactory, but that is a personal, and irrelevant issue.
He may decide to use the factory restore, which should, in the eyes of the law, put him back to the OS he has purchased. I cannot find, on any authoritative pages, including those of MS, as to whether he will then find he has an unactivated OS. I think the answer is that it will be so.
He may then feel he has the right to take the complaint to the retailer.
Interesting though, would be if the factory restore does, indeed, produce an activated OS. If the user has been cunning enough to make an image of Windows 10, he could find himself with two legit OSs on his computer.