It won't have a totally new look if they're really going to film on the south island of New Zealand like the LWW and PC did. I'm excited about the films having a new feel and not having to line up with the previous movies (as this leaves more room for it to line up with the book). But I am a little sad that they won't continue the design motifs of PC and LWW, the art designers at Disney are really top-notch, and the movies at least look good even if they don't necessarily seem to get all of Lewis' meaning.
I think that with nine-ten years passing between Narnia movies they will have change the look just so the movie will look new. Plus, the Dawn Treader movie already had green mist, so they'll have to change the look of that to keep the LotGK creepy, otherwise people will be like, "Aha, we can avoid temptation and the LotGK will just go away!"
"I believe there's a hero in all of us, that keeps us honest, gives us strength, makes us noble." - Spider-man 2(2004)