I'd personally invest time in NativeScript, not because of Angular2, but because NativeScript was designed to work with vanilla JavaScript out-of-the-box, unlike React Native which has a dependency on react.js.
This means that after the initial learning curve of NativeScript, you won't have to ditch your previous knowledge whenever Angular or React get declared obsolete by the community, and people start migrating to "the next cool framework". Some years ago, most of us took jQuery for granted.
Other advantage of NS is the automatic availability of new APIs (ex. iOS 10, or Android N), so you won't have to wait until NS gets updated to take advantage of the new APIs.
Also, I read some claims that "React Native has a longer story than NativeScript", I don't know in which parallel universe did that happen, but NativeScript was released 6 months before the announcement of React Native. [1][2]