Yeah, they've just been down to bugfixing & optimizing for a while now. Dev was already done before it was announced.
Honestly, the main thing that would be "recycled" from Skyrim to "save development time" would be.... their experiences and lessons learned. There's no reason to re-use meshes or textures (given that the new rendering system likely requires new ones anyway). They're unlikely to re-use sounds outside of things that are already in a "stock sounds" library (ambient background hums & wind, etc), plus modern Blu-Ray "damn the space! full speed ahead!" standards seem to be for uncompressed audio. The skeleton's probably tweaked, if the new shooting needs new animations.
But their experience doing all these things in the previous games? Sure, that's always an aid to your next project (well, unless it's an entirely different kind of game, like a 2D platformer
)