On the original question, usually situations like this will depend on the insurance company (if applicable). The insurers will try to recoup some money by selling the trailer/parts/pieces. They may sell them back to the insured or to somebody else. It's going to be the insurance companys call.
IMHO, I would think that just the cost of trying to transport what's left of some of these trailers, would make them want to strike some kind of deal with the dealership........but the dealership may not even want any of it, and just get their place cleaned up, ready for business again.
There could be a demand for RV's in that area right now, as many people lost their homes.
As I look at all the devastation from these tornado's in the news, I'm just glad no more people got hurt than did.