Well, according to Carl F. Hostetter (a source that I trust -- Carl Hostetter works with the Estate with respect to publishing some of Tolkien's linguistic writings in
Vinyar Tengwar) Christopher Tolkien hated The Fellowship of the Ring adaptation by Peter Jackson.
And in my opinion Christopher Tolkien does not appear to be a Jackson fan in general going by his relatively recent statement in a French Newspaper (Le Monde). Moreover, Christopher Tolkien had already stated that, in his opinion, he did not think
The Lord of the Rings (at least) suitable for film adaptation.
So for myself I can't imagine that he would not make it clear, in his will or in another manner, that the rights to
The Silmarillion should be retained as long as legally possible by the Estate, no matter who takes over for him...
... also, Adam and Simon Tolkien are Christopher Tolkien's sons. If anyone is stepping into Christopher Tolkien's shoes here I would
guess Adam.
Guess