I was under the impression part of Bethesda's design philosophy for the Elder Scrolls games was to build an entirely new engine from the ground up for each new game.
Very few "new" engines are written from scratch. Iteration is the name of the game, building on what works and rewriting what you need. Enough code change and it is essentially new; it's all semantics really.
I said the exact same thing in the old Skyrim confirmed info thread (forgot the real name) we had a while back. Nobody believed me, now that the game is out though... they will see.
Spanish is heavily created using parts of Latin. It totally needs the Latin based syntax to function. Stop calling Spanish a language! It is not new, it is just revamped Latin!