Here's the dilemma. If Microsoft starts charging for Windows 10, which is overpriced as is
, then forced upgrades will no longer be possible. Only forcing an unwanted free "product" can be tolerated. Forcing someone to buy a product is against the Interstate Commercial Code unless your name is Obama. Then you can be forced to buy overpriced insurance that you don't need so the people who do need it but can't afford it can have it provided for "less."
But for Microsoft, that would put them in conflict with the law and people would push the issue.
So look for Microsoft to trot out their "Popular demand has been so great that we are continuing to provide Windows 10 for free for the next six months. Or a year. It doesn't matter. As soon as they charge even $10 for the piece of trash growing market share is over.