They will have done a good job covering themselves against class-action lawsuits with the arbitration clauses in the EULA. But one area where I imagine they're vulnerable is when an individual user who was force-fed Windows 10 loses access to some important third-party software or hardware that for whatever reason doesn't work with 10.

Imagine being Stephen Hawking. You wake up one morning to find you've been "upgraded" to Windows 10, and your assistive speech hardware no longer works. That will blow away anything in the EULA, as far as any judge is concerned.

The degree of irresponsibility required to pull something like this is simply staggering.