I think it would be similar to Office.
For example, there would be Windows with a subscription for the activation key. You would continue to get a period of free use (14 or 30 days maybe) before requiring an activation key.
Manufacturers would bundle new hardware purchases with 24 months of credit or something like that, so most people wouldn't notice a change at first.
However, Windows "Classic" would still exist and allow one-off purchases, but may have some limitations to updates or features over time.
For anyone looking for the spider, it's easier to see with the original