The new announcement about the movie doesn't specify who will be involved beyond writer David Magee (Life Of Pi), who has been in charge of adapting the book for some time now for Gordon's production company. But when he made the original reveal, Gordon said that all the elements would be new, from filmmakers to cast. So technically this counts as a reboot, though given the relatively slight crossover with other novels, it could still stand as part of the movie universe already established by Walt Disney Pictures for The Chronicles Of Narnia: The Lion, The Witch And The Wardrobe (2005) and The Chronicles Of Narnia: Prince Caspian (2008) and continued by 20th Century Fox for The Chronicles Of Narnia: The Voyage Of The Dawn Treader (2010). Chronicles Of Narnia: The Silver Chair finds Eustace (brought to life by Will Poulter in The Voyage Of The Dawn Treader) and classmate Jill Pole called to Narnia by Aslan in order to help search for Prince Rilian, Caspian's son, who disappeared on a quest to avenge his mother's death. It is set 50 years after the events of the last story, which means Caspian is an old man while Eustace has not aged.
"Developing this project with The C.S. Lewis Company has been immensely exciting and a real joy," Gordon said in a statement. "We are so pleased to team up with our good friends at TriStar and our partners at eOne to introduce this new, magical chapter of the Narnia franchise to fans around the world, both old and new."