Remember that time Microsoft said Windows 10 would be the last release ever, and that it would be our forever operating system, and it will always just get updated, and it will be around forever and ever and ever as our most special operating system ever?
What they ACTUALLY meant to say is that it will follow the same exact cycle as every other version of Windows.
http://windows.microsoft.com/en-us/windows/lifecycle
As usual, they're winging it and making it up as they go along.