My guess, based on rumor, conjecture, my own observations, and lots of thread posts (translation: my gut)--is that the animatronics will be a combination of old-school animatronics with limited and repetitive movements AND the new projection technology that Disney has started to utilize recently. Both internal projection (think eyes on Potato Head in the TSMM cue, or Mater in Cali Adventure's Radiator Springs Racers) and external projection around a 3-D sculpted object (think of the "Celebrate the Magic" castle projection show, or the cue of Test Track where the basic vehicle sculpted shape changes color and texture based on the person being interviewed in the accompanying movie)
My recollection is that Disney owns a few patents for this technology, and will use it in many more places in the future (this would be a logical application).
Assuming they really are going to be the some sort of new innovative technology that they are touting in the official description, for at least a few of the dwarfs (hopefully all), I imagine a basic all-white head form (or entire body form) on a simple AA body--animated projections will then bring the faces (or entire form) "to life," making them look just like the film. That would be kinda cool, I think.
Just my prediction, based only on my reading of these forums, a little bit of guess-work, and the recently posted descriptions from Disney.