In the windows phone, you can see Skype even on the calling screen, rather than just in apps only. This feature is brought about by Microsoft to make people aware of Skype, wherein you can chat, message or have video calling. But making it visible on calling screen makes it look a bit pushy.
The present Microsoft phones are working on Windows 8 or 8.1 OS only and have not yet been upgraded to Windows 10. Moreover, the Microsoft Lumia phones even did not work well in the market because of some of the apps like FB messenger and WhatsApp not being taken care of by Microsoft.
The devices that are running on the 8/8.1 OS will be disabled from using Skype for video calling but they have the facility to save the chats they receive. Thus, Skype also seems to drop the support. Though, Windows 10 will have the Skype application. This step of removing an app from the older phones could cost Microsoft a switch in users from Windows OS running phones to those running on Android OS.
You can assure the aforesaid by checking out the Skype website wherein they have a Linux app but no windows app. Microsoft comes with a number of apps in Beta form like Xbox beta, now Grove Alpha Music, Instagram is still Beta, so is the case with Skype messaging too. But since it has continued for a period of over 8 months, it is not a cool thing. Something needs to be corrected by Microsoft for Windows phones to have the same success as with the PCs and Operating Systems. For users, Microsoft holds some surprise in its kitty and will be revealing it by mid-year 2017.