Not sure if you saw my other comment below but this is a major goal for us with Elemental. We're not there today, because we're working through the best way to componentize the CSS for each module while retaining a common base for variables & customisation (i.e themes).

The most likely outcome will be to go with the "css in components" approach (w/ Radium, I expect) and maybe a base / "foundational" optional stylesheet for typography / etc. Still working it out though - all today's viable approaches have lots of pros and cons.