You have 3 options if you want mixin behaviour:

- Use old syntax or explicitly add mixin to prototype - Use composition. A bit annoying, because you have to make an extra class

    class OuterComponent extends React.Component {
      render() {
        return (
          <MixinComponent>
            <InnerComponent />
          </MixinComponent>
        );
      }
    }

    class InnerComponent extends React.Component{}

- wait for decorators (?)