Skybox for what...? We use a dynamic sky and using a static skybox for the reflections wouldn't match the world it's reflecting. The screenshots in that link showing screen space reflections don't really make much sense. There are literally no reflections in the image they're showing, instead it seems to show the difference between two different lighting setups...You always could render dynamic cubemap from location of player and use that as fallback solution if screenspace does not have data for reflections.
There is another screenshot http://img23.imageshack.us/img23/935/screenshot0000gx.jpg