Oh yeah. It would be very foolish to not have your high resolution assets available.
For textures, all they really have to do is apply the originals to the models and do some cleanup. For high poly assets, they'd have to reconstruct the whole model using the zbrush sculpt as a base. That takes a lot of time and effort. Not to mention having to reapply all the skeletons for proper animation. I'm sure they still have much of the high poly 1.0 models available, but it doesn't account for all the new stuff they added.