Regarding engines:
Bethesda will never, ever, ever, ever, ever switch from Gamebryo. They will modify the crap out of it. But they will not switch to a completely different engine. Fun fact: Bethesda used Gamebryo in both Morrowind (called netImmerse then) and Oblivion. That engine can and will go a long ways.
Not to mention, they know how to use it. They've said themselves plenty of times that something new and shiny does not outweigh the familiarity and knowledge of use/experience of old and reliable.
TES games have never been about large scale battles.
Seriously, I still have to side with this.
The game is about "I." Not "I and several hundred other sweaty dudes locked in pure uncontrolled combat."