Our plan is to continue support for Angular 1 until the majority of developers have moved to Angular 2. We'll track use by the number of unique visitors to angularjs.org (Angular 1) and angular.io (Angular 2). At the moment, 93% of developers visit angularjs.org.
In addition to several features planned for version 1.5 like component syntax and multi-slot transclusion, we'll release some of the most exciting features for both Angular 1 and Angular 2