In relation to @Praxis 's comment;
Many have been wondering this for many years, and in a few podcasts about science fictions I've heard people point out that opportunities for screen treatment lie within L&F Men/Star Maker. Entire novels/films could be made from nothing more than a couple of pages...
To the point: I actually reached out to someone acquainted with the George Pal estate, inquiring about the film rights to Odd John. It turns out that the estate had received interest from a few parties, though nothing came of it. That contact also mentioned that it was getting a little tiring; each time a party expressed interest, the estate has to bring in the lawyers, costing money.
Given that nothing had come of it (at least at that time) the estate was a little leery without legitimate interest from a production company.
A Side Note about Screen Treatment for Sci-Fi Drama
Two novels fitting the same general type as L&F Men/Starmaker have been pursued in earnest over the last couple of decades. These examples highlight some of the challenges:
Sirens of Titan - Vonnegut
This novel has been in the works for almost two decades, changing hands twice; then a third time. Hollywood and Vonnegut. The key is that science fiction invoking depth and drama has tended to gain little traction outside a few examples. There just seems to be so many challenges.
The Sparrow - Mary Doria Russell
This is a modern, yet hugely successful work (within the realm of its 'market.') The author has fielded interest in an adaptation of her work for decades as well.(Her own chronology on her blog since 2010).
Comparing Stapledon's work to Russell's, it's worth noting that most of his novels lack strong characterization; Russell's in comparison is utterly loaded with it. Though, some of the controversies in The Sparrow may be holding it back. But there does seem to be some real traction, something that can't be said about any of Stapledon's works - at least since the 1960s.
I've even seen some posts in adapting Stapledon's work in and around Reddit.
Such projects are massive, and even when funding becomes a reality, it gets caught in an avalanche how best to do it. I too would love to see something adapted. But I'm partial to suggestions by some to start with graphic novels, which might be a good way to prototype a larger adaptation.
All in all I'm with you. His treatment of cosmic themes, multiple universes, genetic modification, telepathy, terra-forming are simply outstanding. You get the feeling something can come of it, but maybe a film isn't the best start? Just a thought.