I'm here to say it is not!
The next movie will be The Magicians Nephew.
Source: link
link
Fox (instead of Disney) decided that they will be skipping the Silver Chair and just going on to the Magicians Nephew.
I am very sad that the Pevensie will not be there.
I think another reason they are doing TMN is because many people say it is their favorite book after LWW.
Fox is hoping that TMN will have a better turn out than the Voyage of the Dawn Treader.