At this point the the MVC6 is still not official.
You could check this article
periodically for updates. As well as follow our GitHub to see what is already available.https://github.com/telerik/ui-for-aspnet-mvc-6-demos/releases
The TreeView as well as the other missing components will be added in the upcoming release. And they will sure be in the suite when asp.net 5
have its official release.
Do you want to have your say when we set our development plans?
Do you want to know when a feature you care about is added or when a bug fixed?
Telerik Feedback Portal
and vote to affect the priority of the items