By dumping the license, SCE&G is eligible for a $2 billion tax right off. In order to do so, they have to show that they have completely abandoned the project and this is a major step in that process.
As for Santee maintaining the site, estimated cost is around $15 million/yr. Santee currently has over $8 billion in debt, so I wouldn't hold my breath on that one.
To quote one of our previous GMs, "There isn't a white knight riding in here to save this thing. It's dead."