According to an unofficial source, but someone that seems to get a lot of facts correct and be in the know about many things, “The Magician’s Nephew is in development & The Silver Chair is in script stage.”
This is very interesting, and we can only guess at what it means beyond the simple text. When a film is in development, it can mean many things, as the list of films “in production” on IMDb Pro includes films at many various stages. In fact, as of this writing there are 141 pages of films in production with about 30 films per page. It can mean practically anything. A film listed here may not be green-lit yet, but the next phase is pre-production and that is followed by filming, post-production and release.
Script stage just means that they are writing an exploratory script, likely the first draft.
It is likely that the person who tweeted this got the information from IMDb Pro, however, so we should all take this with a grain of salt, no matter how excited we are at the prospect of the continuing of the Chronicles of Narnia on the big screen.
I responded that I was very excited to see something about the possible continuation of the films, to which he responded: “Me too. But these are very early in development. It doesn’t guarantee they’ll get made.”
Larry 411’s “Source for MN info is Walden, source for SC is Fox 2000.”