According to this screenshot of a tweet (his twitter account is private): “Completed the final draft of The Silver Chair today. I’ve had the immense pleasure to work on the project for over a year now. So fulfilling.”
We confirmed it with David Magee through his public facing twitter account (the account this appeared on was one for family and friends only).
The film is without a cast, director or major motion picture studio at the moment, with the Mark Gordon Company being mostly a television studio.
The last rumors that I heard were that Sony Pictures was in the running, after most other studios had passed on the project. There is no word if that’s where the project has settled. For the moment, take all of this with a grain of salt. We only know what our sources have told us, and nothing more.
Update (June 28, 2015):
The official Narnia facebook page has been updated to deny that the script has been finished by David Magee. Either there has been some hacking, or some false accounts created speaking on Magee’s behalf in an elaborate con by some kids hoping to cause a stir.
The bogus report of David Magee's #SilverChair finished script is a scam. Always follow The Chronicles of Narnia @officialnarnia & Narnia.com for all official movie news #NarniaMovieNews
Posted by The Chronicles of Narnia on Sunday, June 28, 2015
Like we said before… take all of this with a grain of salt. The thought that more Narnia was coming was fun while it lasted.