The iOS and Android part don't make sense to me. Surely you won't be running VS on your iPad? So are they saying it has support for compiling to iOS and Android? Wouldn't they need to mention Xamarin in that sentence for it to make sense?
My money is on the App Creation naively in VS 2015 - via Xamarin or similar plugins - instead of having to rely on tools like Eclipse or IdeaU.
I think I'd lose my mind if I could develop apps in Visual Studio and C# instead of having to use Java and pay $1000/year for Xamarin.
It could just mean a move away from Xamarin as a core development tool into producing things which support development on these platforms.
What will likely happen is Microsoft will :
* open source the core libs
* open source the JIT
* make sure it works on all platforms
* open source the ASP.NET and port it to Linux/Mac so they can separate Azure from being a Windows only cloud service
Xamarin then packages these in to Mono and Xamarin.iOS/Android providing a layer on top of MS core stuff. Microsoft will then be able to sell .NET as a truly cross-platform solution and make VS/Azure more popular where it's probably losing to other OSS ATM.