I've thought a lot about how Seveneves could be adapted, and man ... it's going to be a tough thing to pull off. A movie trilogy might be able to cover half of it. Were I to do it myself, I'd probably go for a three-season TV series, with each season being one of the parts of the novel. I have no doubt that there's a ton that can be cut from an adaptation, but I'd be hard pressed to cut much, personally. I'm very bearish on any potential adaptation to a single film, as much as I'd love to see one happen.
Whoever attempts it should try soon because then the people that Stephenson actually modeled his characters after could play the roles in the film/TV series. For instance, one of the characters in the first part of the book is obviously modeled on Neil DeGrasse Tyson.
yeah. Even that head of rocket company seems to be a bit inspired by Blue Origins/SpaceX. Neal has worked for Blue Origins in some capacity. Also, TV series would be much better because it's spread over a number of episodes giving a sense of time.