Originally Posted by Motoki 
Yeah but they kind of go together in some sense. You can transfer a UI or parts of it to a degree with the same engine but it's not as easy to do when you are moving over to a completely different engine. You pretty much have to rebuild it.
Not trying to get into a debate, but I will just point that you *can* really put a vastly different kind of UI and controls on a same engine. You just need to look at the Unreal Engine 3 for instance which has been used for pretty much any kind of gameplay imaginable with vastly different gameplays and UIs.
That's not to say they wouldn't recycle the DSIII UI if they felt it appropriate, but if they aim for a different kind of game, they'd probably go with a different UI (the Alien RPG UI was nothing like it, and it was the same engine)
So I wouldn't worry about it really.
-Sergorn