I especially liked this part of the article: Correspondingly, The Magician’s Nephew needs to be read later, only after we have encountered the magical wardrobe, the mysterious lamp-post, the evil Witch, and the oddly sympathetic Professor. After The Magician’s Nephew gives us the story of their origins, we can say with satisfaction and delight, “So that’s where they came from!”
So what? For The Magician’s Nephew to resonate the way Lewis intended, its audience must have the elements from The Lion, the Witch and the Wardrobe still firmly in mind.
Walden’s film adaptation of The Lion, the Witch and the Wardrobe released in December 2005; The Magician’s Nephew is tentatively slated for December 2013. That’s an 8-year gap. How long can cinematic memory be expected to last? Had Walden kept The Magician Nephew as sixth in the series and released it sometime around 2018, there would have been a 13-year gap—and a whole new generation of theatergoers would see it without having seen The Lion, the Witch and the Wardrobe in the theater.
That is why it can be argued that Lewis would agree with Walden’s decision to make The Magician’s Nephew next. The audience needs to still strongly remember Wardrobe for Nephew to work best.