Six years after Voyage of the Dawn Treader, a bunch of studios and production companies (TriStar Pictures, The Marc Gordon Company, The C.S. Lewis Company, and Entertainment One) have teamed together to get an adaptation of The Silver Chair filmed. Their intent is to have this be a reboot of the franchise which is convenient since only one character from the previous movies comes back, and he can be recast.
David Magee finished a script last year and that's about the only news. No director or cast or main executive producers.
The Silver Chair follows Eustace (cousin of the Pevensies) and his friend Jill as they go to Narnia to help find the lost Prince Rillian, a descendant of Caspian.
I know it's a reboot, and he's too old/busy, but I think making Poulter come back would be hilarious