Posted by: @lentenlands

The Walden films overall emphasized actor, music, and overall style continuity (arguably to a fault in Dawn Treader)

Could you explain what you mean by this? Because I felt like VDT had a really different visual style from the first two movies. Everything is very pastel colored and shiny where it looked and felt more solid and realistic in LWW and PC. And while they had actor continuity in that they had four of the same actors back, Edmund and Lucy were performed very differently to the extent that they felt like different characters.

I'm sorry if it sounds like I'm bashing the VDT movie. The third Narnia story is supposed to be different from the first two. They were both about political conflicts, ending with wrongful rulers being dethroned and rightful ones being crowned. The Voyage of the Dawn Treader, on the other hand, is about a voyage into the unknown. Some stylistic differences make sense. (Though I must admit I do consider the acting, visuals and music in the first two movies superior to the third.) 

Anyway, I have mixed feelings about what you're suggesting. I know some people like Michael Ward stress the differences between each book and I can certainly agree to an extent. But I do feel like the books share a specific style despite they're varying content. Some are darker and some brighter. Some are more character driven and some more plot driven. But you can tell they were all written by one author and all take place in one world. (Well, technically, one multiverse. You know what I mean. ) 

It's also worth noting that despite the huge time lapses, not much changes in the world of Narnia between each book. While they're not described in a lot of detail, you get the impression that clothing and architecture styles stay the same from the beginning of history to the end. (Edmund and Lucy are able to tell that the Dawn Treader is a Narnian ship just by looking at it, even though there haven't been any Narnian ships for who-knows-how-long.) The kings of Narnia and Archenland are always good and always allies. The Tisroc is always evil and always want to conquer Narnia and Archenland. The only major change I can recall is that talking beavers (and nontalking beavers?) go extinct, as do some of the more exotic animals in The Magician's Nephew, like elephants, apparently.

I guess my ideal would be a limited number of directors/writers. (Having only one for seven stories is too much for which to ask.) But-and this a big but-have them not be afraid to tell different kinds of plots in different locations with different characters. (I say plots instead of stories since all the Narnia arguably tell the same kinds of stories. They all have happy endings and lack moral ambiguity.) 

We have a discussion about what Netflix should and should not do in Hopes and Fears of What will Happen in Narnia Movies.

We expect changes to be made, because that's what adaptions do. As @col-klink mentioned, well, I wouldn't bash Voyage of the Dawn Treader movie. I'd liked it fine, maybe not just as much as the previous two.

There could be a concern that they make the franchise a saving the world type story, though. While The Horse and His Boy is kind of a saving the world story, it should really be about Shasta making this journey to Narnia and the North to make a discovery about himself.

Posted by: @lentenlands

... one way to demonstrate that this is a different franchise would be to get a different director (with their own style) for each one.

....

Now, of course, they should still keep the same cast and all be in continuity with each other...

I like that idea, but I would actually go all in on the concept and get a completely different cast, crew and production for each one. You could then essentially do it as an Anthology Series and choose a visual style unique to each book.

Way back when The Matrix first came out they did a spin-off project called The Animatrix, a prequel series where they got 7 different directors to tell 7 different stories in completely different animation styles. It was a lot of fun from what I remember.

But as well as just being a fun artistic concept, I think something like that could work well for Narnia, as it would essentially make the storytelling as significant as the story - and I think that's one thing that has always separated Lewis from, say, Tolkien - that Narnia is not so much about the deep lore and mythology of the story, but much more about the storytelling and Lewis's own narration.

The idea of each film having a different director is interesting in theory, but it also seems risky. I can imagine really liking one director's take on Narnia and then wishing that same director had been able to make all of them. On the other hand, if they don't pick a different director for each movie and they pick someone whose vision of Narnia I don't like, I'll be stuck with it for potentially seven movies.