That's what they mean. You are listening/reading into it too much. Every Windows has a number of years for support, and this number can change. The number has never decreased and has only increased in the past because people/companies were too slow at getting rid of old Windows (e.g. Windows XP). We do not know what the actual number of years Microsoft is going to support for Windows 10, but I bet it's going to be around 10 years just like other Windows.
Check http://windows.microsoft.com/en-us/windows/lifecycle for the current list of Windows.