I think you can, and I think they do; but that still doesn't solve the memory issue, actually it makes it worse since now you have to store multiple 'resolution' versions for the same data.

But if they still need to use 'traditional' techniques like LoD, rendering at various resolutions, etc, then the complexity and running speed can't be all that much faster than a traditional approach. The way I've been reading these articles is that somehow he's got a very fast method of deciding which voxels to show, without any pre-processing or optimisation - just brute force. I'm curious to see the first demo they'll come up with, especially since they only now seem to be at a point where they can render without shading, animation etc, and they make it seem as if those are just implementation details that can be added on an afternoon. We'll see.