Judging by the high prices of soft portrait lenses versus normal sharp lenses, I would think we're in the beginning stage of some sort of revival for it. Whether it goes mainstream is not certain, but the cult following for soft lenses is certainly quite strong. Higher prices must mean an increasingly healthy sellers market for the stuff.
Maybe part of it's a natural cyclic fashion thing.
Certainly part of it is a repulsion from the perfection and ubiquity of digital imaging.