I want dinner, for one. But other than that I'm not sure I was looking for anything in this thread. Just making a pretty obvious statement that after breaking monetary records Bethesda is surely in a position of "It's not broke, so we're not fixing it."

from a " business practice" stand point, why would they change a successful formula

Bruh, that's my whole point. They wouldn't. How have you missed this?

I've heard this since Morrowind's release. And they have improved the engine with every release since. The engine has been built to cater to the kind of games they make. So why would then not continue to improve the engine instead of starting all over from scratch? They know this engine inside and out. They know each and every thing they have done to upgrade and improve it. They know what works and what doesn't.

Looking at it that way, I don't want them to change to a new engine. It would be years of work, improvements, tweeking and most of all knowledge thrown out the window.

From an http://www.ausgamers.com/features/read/3526651, it looks like idTech has already been considered and rejected as not suitable for games like Skyrim or Fallout, but they have had advice and assistance from id's software engineers when they thought they needed it.

Personally I doubt if changing the game engine (which part of the game engine?) would do anything to address the issues they have with animation - unless the Havok Animation Studio middleware is notoriously poor? If not, then it's what they're doing with the engine that people have a problem with, not the engine itself.

Remember, the so-called Creation Engine is a whole suite of in-house components and third-party middleware, and I'm not sure that there's one single part that's remained unchanged since Morrowind. We don't even know yet if they're still using for Fallout 4 the customised and extended model file format which was originally based on NetImmerse. But even if they are, that says little about the code that's making use of that model format.

Very impressive numbers there.