I doubt Beth would remove moddability like that: it'll just take some getting used to the new tools, I reckon.
Seriously, the news that this is a new engine is like music to my ears.
The CS will be no problem, I'm sure. What I'm worried about is modeling: .nif/.kf are Gamebryo formats, so we will need all new exporters for Max, Maya, and Blender, as well as a new Nifskope equivalent. Considering how long it took us to reverse engineer what we know about .nif, this could be a
major step backwards.
On the other hand, this could remove some of the problems with releasing an official exporter :shrug: