Windows 8 App Store certs replaced by Windows 10 App Store certs...
Looks like these are being replaced by UWP certification - just a case of moving from Windows 8 app store to windows 10 app store.
The mew MCSD includes the C# Specialist 70-483 exam plus two new ones: 70-354 Universal Windows Platform – App Architecture and UX/UI and 70-355 Universal Windows Platform – App Data, Services and Coding Patterns
https://www.microsoft.com/en-gb/learning/mcsd-universal-windows-platform-certification.aspx