For modeling it's the present

For rendering , C4 , do a great job !
For terrains you can do complex one without putting additionnal meshes on top of it.

Jhon Carmak talked about Voxels for rendering today games ?
I don't see the advantages over polygons, and for storing characters perhaps it will take lot lot more data.
Another thing : how will you have shadows and shaders with voxels ... Well , we can wait , that's not for tomorrow