So the result is, that if there is going to be any realization of that value, the legal owners of the copyright need to cooperate with the legal owners of the negatives.Not true:
"The probate case that has played out in Chicago has added another layer of intrigue to Maier's story. At the center of the case is an unusual situation: A woman who died virtually penniless and without any clear heirs now has an estate potentially worth millions of dollars. But while the estate has the copyrights to Maier's work, others legally own the film itself."
http://www.chicagotribune.com/news/...an-maier-estate-fight-met-20160526-story.html
There is nothing particularly unusual about that in the realm of copyright - just consider the recording industry, where the recordings are owned by the recording company (or at least they used to be) before they are sold to the consumer.