If they do end up significantly abbreviating the scenes with Aslan, I'm going to be seriously annoyed because I just don't think that the expense of CGI is a good excuse.
There are ways of creatively capturing the essence of a scene without relying on special effects, and there are ways to indicate the presence of Aslan without always having him onscreen in all of his pricey, golden glory.
For instance, when Aslan first appears in
The Silver Chair to blow Eustace into Narnia, Jill doesn't even recognize what kind of creature it is at first—it's just a "huge, brightly-coloured animal" bounding to the edge of the cliff. She does discern that it's a lion before Aslan returns to the forest, but it occurs to me that obscuring the identity and visuals of Aslan, at least in the beginning, could be helpful for a number of reasons, special effects expenses being one of them.
The other would be the fact that when Jill initially encounters Aslan in the forest, she believes he is going to
eat her. While I don't like the idea of making Aslan seem more threatening than he was in the book, or make him appear that he's trifling with the poor girl, I do think that having Aslan largely unseen and unidentified at first would really help with causing the audience to feel the same fear that Jill feels.
It's possible that she wouldn't even see him at all by the cliff, but be aware of the sound and force of his breath, and with the camera angled in the direction of Eustace's disappearing form, the audience could just get a glimpse of something large and golden appearing behind Jill and causing a great wind. Then, when the wind is gone and the shape of Eustace has disappeared, Jill turns to look and only sees the back of an animal disappearing into the wood, and maybe even the footprints of a very large feline predator left behind.
Their initial conversation when Jill is dying of thirst could take place with Aslan largely obscured by the underbrush of the forest, with his voice coming from various angles as if he is circling her, giving the audience the impression that this is an animal stalking Jill, and that there is nowhere to run because the voice is coming from all sides. Then, once she has finally taken the drink from the stream and looks up, have Aslan be fully revealed, waiting by the water out in the open, looking exactly as Lewis described him—sitting like the lions in Trafalgar Square, bright and fiercely beautiful.
After this point, I'd like the rest of the conversation to progress pretty much as it does in the book, though you can always take advantage of focusing on Jill's face frequently and as well as wide shots to cut down on the amount of time a very detailed CGI Aslan is on screen. You could also cut out the visual of Aslan when Jill is walking towards the cliff, setting up the scene as if Aslan is carrying the camera, and when she turns to say goodbye, show Aslan as just a golden speck on a cliff that's already a hundred yards away, as the book describes.
Now, I'm not exactly an expert on filming or how to set up an impactful scene, camera-wise, but it seems to me that the above could be a decent example on how to cut down on the presence of a pricey CG lion without cutting down on the presence of the
character of Aslan at all.
Goodness, this post ended up so much longer than I intended... I love dreaming about what the film might end up like.