- use require() to import your files and your deps
- migrate to webpack could help the first part
- use only npm dependencies, deprecate bower
- use ES6/7 using babel
- use directive or component (>=angular 1.5) for everything, you can use component on uiRouter in the alpha version
- use Redux to handle your state - https://github.com/angular-redux/ng-redux, prefer one binding instead of two-way data binding for directives/components on angular
After this you could follow two paths:
Use ngReact and mix angular with React, I don't like this approach.
Or you can start a new project from scratch with hot reloading, because the Redux code will the probably the same, and it will be easy to convert a directive/component with only one-way databinding to a React component