At least those 900 million Windows 10 users have another year before support ends—absent a surprise Microsoft support extension, an affordable support package or a workable workaround. But for 50-million Windows users that end of support nightmare has come true, and Microsoft is warning them of the consequences.

The endless cat-and-mouse game between Microsoft and the community of devoted Windows hackers just took another turn.

"On new Teams, users on OS versions that are not supported will receive in-app notifications to encourage them to update their device to a supported OS version. A version that is too far out of date will become incompatible with the service and the Desktop client will be blocked until the OS is updated."