I wonder what would happen...
What if vendors explained out right, with a prominent sticker on the computer, that they have made machines for windows only, and then said: "Boot any other OS, and your computer will need physical repairs". Further to explain that the decision to run windows and only windows, removing their choice, has been taken for them.
Further explain that as the computer ages, the usefulness of it will be limited to the latest windows it can run. Explain again, that even if Linux could give them a bit more out of their hardware as a home server or a backup, Linux can't be run at all.
How much market would they loose? For sure, they would loose me without hesitation. But how many people would be offended/disturbed that their right to do with their hardware as they please is taken away by careless manufacturers? How many windows users will care to choose manufacturers that respect their clients property rights on their computer, and give them the ability to choose their OS?