There are a number of options for switch boxes that don’t have a neutral. One of the best, Lutron Caseta, is unfortunately not currently compatible with smartthings, although there are a couple of possible workarounds.
That said, very exciting news just today, because the Lutron booth at CES 2017 had a smartthings hub on it! Now confirmed officially, for release “soon.”.
That would be a fantastic integration which many people have been asking for since SmartThings started, and basically solves the retrofit issue if it happens .