Windows 10 and 11 both try to trick you into switching from a local login to a cloud login. And in that process trick you into putting your Documents, Desktop, etc into the OneDrive cloud. As you run out of space, your connected Hotmail/Outlook account will shut down until you pay them to increase the space.
My Dad's 80+ year old neighbor had this happen to her. She couldn't figure out why she wasn't able to email pictures back and forth with her daughter. And she was already paying for Carbonite cloud backup. It took me an hour to get it all sorted out.
Windows N+1 will share a majority of code with Windows N. Microsoft would now have to maintain two copies of the code N and N+1. This is added cost.
Alternatively Windows could do continuous releases, but this is less fun to market, and users might not like big changes happening many times a year instead of all at once, etc. There are also compatibility challenges for this since behaviors are tagged to such specific versions.
The problem isn't the EOL. The problem is that the newer versions of Windows are user-hostile and the alternatives are being retired.
Or is this hypothetical?