I believe those databases are the property of the USGenWeb. After reading RootsWeb's Terms of Agreement, concerning their server space, RootsWeb does not lay claim to any of the content stored on their server. Unlike how Yahoo slipped that ownership clause into the GeoCities Terms of Agreement. I'm think that MyFamily will promote those projects by placing links to it from their other sites. They may even be able to convince the USGenWeb projects and coordinators into staying on RootsWeb by allocating funds to their projects.
Extreme care needs to be exercised.
There's too much room for corruption here. Actually I expect that Ancestry will do everything in its power to keep the stable of volunteers happy. I doubt any money will change hands but its too valuable of a resource to let slip. Ancestry used to have its own sort of program in which a person could give data and receive free a membership. I don't think that program is alive anymore but perhaps the county or state coordinators could receive free access to Ancestry.