A whole can of worms...
I work for a small company and I know for a fact Barclay's business banking website does not support Windows 10. The accountants machine is the only machine in the company that is still on windows 8.1. Now if Microsoft was able to force a windows 10 upgrade on it, it would have serious implementations on payroll & the accountants ability to work.
Sure the machine is locked down and shouldn't allow the accountant to run the update, but Microsoft is getting awfully aggressive with their forced upgrade policy.