The reason this is pretty shocking news is that Disney, having purchased 20th Century Fox, owns the rights to Planet of the Apes and is, in fact, developing a new film version. Somehow, though, the Boulle estate seems to have retained the rights to Planet of the Men and has therefore been able to make this deal with producers Uri Singer (formerly of Luc Besson's company and currently head of Passage Pictures) and Aimee Peyronnet.
The challenge that Planet of the Men is going to face is that it was designed to pick up where the original Planet left off, following the trek of astronaut George Taylor (Charlton Heston) and the primiitive human Nova (Linda Harrison) into the Forbidden Zone. (BEWARE SPOILERS): There, Taylor encounters a group of non-subjugated humans, affording him the capacity to preach and pontificate and begin a future he might be able to believe in someday. Meanwhile, the City of Apes is in social disharmony, thanks in large part to the unrest seeded by Taylor, and chimpanzees Zira (Kim Hunter) and Cornelius (Roddy McDowall) in the first film. Word of Taylor's influence amongst the growing human civilization in the Forbidden Zone is stirring the apes into a frenzy. They ride out to squash his increasingly organized and effective "resistance" — a (somewhat) manufactured crisis intensified when the apes realize Taylor and Nova now have a child, Sirius. All hell breaks loose.
The ape attack unfolds poorly. When apes understimate human rage and ingenuity, their attack goes sideways. The humans, having learned that Taylor had once befriended apes Cornelius and Zira — and willfully refusing to accept that not all apes are "bad" apes — turn on Taylor, killling him, and attack Ape City, evoking notions of cultural/primal memory. The now subjugated apes revert to a closer semblance of their basic animal state. All concluding with the noted return of Dr. Zaius (Maurice Evans) to his more primitive roots.
Ironically, what didn't really work as a screenplay, if fleshed out properly, could make a very intriguing television series that unfolds over time. It will be interesting to see how much of Boulle's work actually makes it (legally) to the screen — and how things unfold.