From what I have seen (all the live-streams, and posts / blogs from Radiant) it seems that their is no voxel engine in game in so far as models or non-terrain objects. It seems there may eventually be scripts / utilities for converting Qubicle models to game models but that they are standard 3D models that just happen to be based on voxels. If my assumptions are correct there would be no reason that you couldn’t make a mod that would use non voxel based models. I’m not sure if the game engine would support textures on the models, or that the engine only renders RGB values on each surface.
Anyway, just an interesting thought. I really like the voxel look of Stonehearth and Tom (I’m pretty sure it’s Tom, I can get them mixed up) seems to be doing an amazing job with art direction and giving the game a very consistent look throughout. Much better than any of the plethora of Voxel based games that are out there. Something to think about in any case.