According to Microsoft, Every Windows product has a lifecycle. The lifecycle begins when a product is released and ends when it’s no longer supported. This date to end the sales of the software (Windows 7 and 8) was announced sometime ago.
The next version of Windows, called Windows 10, is due to be released in late 2015. Looks like this change is to clear the path for the arrival of Windows 10.
The only exception would be retail box sales of Windows 8.1 (Different from Windows 8.0) and businesses and consumers will still be able to downgrade to Windows 7 Professional but at an additional cost and have limited availability.