I can see Microsoft doing this TBH, they've changed a lot these days for the good!

Skype has really become garbage with the new update. I think most of their dedicated user base is leaving. It looks like MS is making similar mistakes as Google concerning their consumer messaging services

Skype would be a terrible addition. Skype uses H.264 AVC versus H.264 SVC. The issue here is that AVC isn't industry standard; SVC is. This makes Skype a "walled garden", just like Hangouts. The best addition would be Jabber.

Also, Skype's video quality is not that great tbh.