They are actually using Typescript, and this will lead to less friction wrt hiring devs, supporting all those platforms and integrating web components. Still I would have hoped that MS would be a little more forward thinking, and put some of their MSR tech in good use, to encourage the use of better languages. Just like how Facebook is pushing ReasonML.

I think that the C# focus of .NET is a major mistake holding the platform back, especially when we have languages like F#, Scala, Swift, ReasonML and Rust these days.