The point is that approaches such as "SUV's bad, kids good, let's blow 'em up" is simply not capable of reaching the deeper emotional and intellectual chords struck by a Gandalf or an Aslan even within quite young children. Art tells.
I do not personally share the author's enthusiasm for The Last Battle - it's brilliant from a Christian perspective but inherently dark and, I think, not entirely appropriate for young children. It is, after all, about the death of their beautiful fantasy world and the afterlife for those who choose belief. That's some mighty heavy lifting for a kids' movie. I doubt it will be made but I might be wrong.
Prince Caspian, however, evidently will be next which is logical enough given that it requires the present cast to be pretty much their present ages. Harry Potter is doing astoundingly well dealing with the advancing age of its cast (IMHO) but five years' delay for Caspian would probably be a bit too much to incorporate into the plot. It is also fairly light on the Christian metaphors, at least as Narnia goes. Looking forward to it.