Scala can be very good at interop - I still use Wicket (Java) for my Scala web UIs. And I'm confident that the Scala.js folk will have a good answer for doing UI, whether that ultimately means Angular 2, another existing framework, or a native Scala.js UI framework.
All that said, if you're thoroughly committed to Angular 2 (a mentality I don't really understand - I love Wicket but if an equally OO framework existed in native Scala then I'd use that instead) then using anything other than Typescript is probably an unnecessary risk factor.
I'm more into a long haul so scala sounds pretty cool.
But what just rushed into my mind is that angular 2 will be in typescript so learning scala would only be relevant for server side code. And using two languages when one can handle both doesnt sound quite convicing :/ Would you still recommend scala when I want to work with angular 2 in the near future?