Microsoft has not been offering mainstream support for Windows 8.1 for a few months now, but it has still been accepting new Windows 8 apps into the Microsoft Store. That will change October 31. Microsoft has announced that it will no longer accept new Windows 8 or Windows Phone 8 apps after that date.
Developers will be able to continue updating old Windows 8 apps for a little while longer. Updates for Windows 8 apps will end July 1, 2023, and updates for Windows Phone 8 will end July 1, 2019.
The announcement added, "We encourage you to explore how you can port your existing app to the Universal Windows Platform (UWP) where you can create a single Windows 10 app package that your customers can install onto all device families."