Skybox, HDRi and Shadows

Hello everybody,
First of all, I thank the developers behind this project, I am very excited about it.
I know skybox sources supports only cubemaps but I wonder if we can use it not only to light the scene but also to cast shadows like a HDRi map would do in a 3D rendering software (e.g. Vray). And if so, how can I do that ?
Also, is it planned to add support for HDRi maps for skybox sources ?
Thanks for your answers !