Greatest hope - that the creation of Narnia scene delivers something truly spectacular that blows people away. You know, the sort of scene that has people talking for days, like "you just have to see this on the big screen".

Greatest fear - that Narnia ends up as another piece of disposable Netflix "content". I feel like Netflix have very occasionally produced some great films (GDT's Pinocchio is one) but all too often they end up producing algorithm-friendly mediocrity, which gets quickly forgotten about.

Greatest hope - My biggest hope for Netflix’s The Magician's Nephew is that it offers more than just a visually stunning fantasy—it should be a story that resonates on a deeper level, exploring themes of grief, power, and friendship in a meaningful way. If it’s a truly great movie, it will introduce an entirely new generation of readers to the series.

Greatest fear - My main concern is that Netflix’s Narnia might lean too much into a dreamlike, Wizard of Oz-style aesthetic, where reality and fantasy feel blurred. This stems in part from Greta Gerwig’s deep love for The Wizard of Oz and her comments about wanting Narnia to “feel like magic.” While I appreciate that she’s focused on creating a sense of wonder, one of Lewis’ greatest achievements was making Narnia feel like a real place—both magical and tangible at the same time. 

If I had to pick just one hope, it would be the sense of awe and discovery. More than any other Narnia book (Dawn Treader is a close second), The Magician’s Nephew is about witnessing something new—we literally see the death of one world and the birth of another. I want them to linger in those moments. If those things don’t feel magical and weighty, I think the whole film risks feeling flat.

I really, really don’t want them to make Digory and Polly older. I get why adaptations do this, but part of what makes The Magician’s Nephew work is that they’re children experiencing these massive events. Making them teenagers would change the entire dynamic.

Also… please no awkward forced romance between them. They are friends. Let them stay friends.

Greatest Hope: Atmosphere, atmosphere, atmosphere!  I really hope the atmosphere of London, Charn, Narnia, etc. as well as the characters themselves are done right! I also hope that the talking beasts, (Aslan in particular) look good. I don't want to simply see a CGI animal in which their mouth moves (ahem, The Lion King). 

Greatest Fear: I really hope we don't see loads of CGI/something that looks like a standard fantasy/Marvel movie. 

Greatest hope: Aslan's tears. I have no idea how they'll convey grief in the face of a lion but I really hope they do so in a way that shows Aslan not only understands Digory but shares in his grief and genuinely feels the pain with him. 

Greatest fear: Jadis. Similar to Impending Doom I don't want her to come across as another 'Wicked Witch of the West' but actually have the commanding presence and fear-inducing aurora of someone who destroyed her own world with one word and would have no issue doing the same to another. 

My greatest hope: That they will bring alive the different ages of the world of Narnia and how they change and progress, through the costumes, look and design.

My greatest fear: This might seem unusual to most people but, I think Greta will do alright with the story in general. I think that I am most worried about the overall look of the movie. That the movie will not look like Narnia, but, instead feel like some generic fantasy movie. Narnia is not just a pg version of Lord of the Rings or like all the other fantasy stories out there.

Hard to pick greatest hopes and greatest fears... I'm not even fully sure I covered them thoroughly or that I make much sense in what I've written below, but hopefully it does make sense.  

Greatest Hope: For me, two things, firstly as Aslan - as others have stated here, that he be done right - or at least, they do him justice in his portrayal, from how he appears on screen to how he interacts with the characters - sharing in the emotion with Digory for instance.  Being one who should be feared, respected and honoured.  Appearing wild and good.

The other greatest hope is that both our world and the other worlds Charn and Narnia (and the Wood between Worlds) appear real - in the sense that, yes these are fantasy stories, but no they're not dreams and neither should they be portrayed as such - no Alice in Wonderland or Wizard of Oz style twists...  This needs to be done - having them appear real, whilst also capturing the wonder, magic and mystery of the beautiful world of Narnia.  This second one is I suppose partly a greatest hope and partly a greatest fear...

Greatest Fear: That there will be unnecessary changes, like Walden completing changing the story of VDT from the book - it almost being nothing like what it was "based" on.  I understand some changes are necessary to translate book to film, I don't expect for the film to be word-for-word from the books, but I would like to see any changes they make from book to film be in line with the heart or nature of the books.  And also, that they don't rush over, the magical, emotional and or heart-warming moments - for instance Aslan's resurrection in LWW or when they're travelling by night to the stone table and sleep in the beavers hide-out.  And similar scenes in MN - when Fledge and the children are settling down for the night on their journey to the garden, hearing the noise of someone nearby, and then watchful Fledge listening whilst the two children go to sleep.  Don't skip or rush over these sort of scenes for the sake of action, action, action.

Greater hope: That Greta knows how to make the transition from an innocent movie of children meeting each other to a somber one about a destroyed world and finally, the rebirth of a new world full of magic.

Greatest fear: the character of Jadis. It's complex and difficult to portray since in the role of the magician's nephew She is a little unstable like Lww Jadis. I don't want a generic witch, i want a witch who shows herself to be unstable and then learns how to do things.

Greatest Hopes:  The movie needs to be fairly accurate at recreating the original story. This means that it will have the same story with no unnecessary alterations to the plot. The characters should also be as convincing as in the original story. I hope that some really fine actors will play the most important roles.

Greatest Fears:  I hope the movie will not turn out to be like the “girl power” version of The Silver Chair that was cancelled. I was glad that Douglas Gresham was able to help prevent that movie from being made. I am actually afraid that someone might try something like that again with more films made from the Narnia books. By giving Aslan a more prominent role attempts to overly humanize the movie could be avoided.  Aslan should always be the most important character. 🙂

Greatest Hope: I want to feel the spirit of C.S. Lewis in the movies. I want Lewis's beliefs to remain intact. I want Narnia to be its own world, not copied and pasted from some other big fantasy movie. I want the dark parts to be dark. I want the joyful parts to be joyful. I want NARNIA to come to life and for little kids to go peek in their own closets when they think no one is looking after they see the movie.

Greatest Fears: With Gerwig in particular, that it will be TOO artsy, TOO out there, and too full of her own beliefs and prerogatives. And on the other side of the pendulum, that it will be just another mediocre fantasy film. 
(As an aside, I'm not too concerned on the latter for the first two movies, but if Gerwig is successful and then she moves on, I'm very concerned about another director coming in and not doing justice to the later Narnia books.)

to be successful , imho, we have to believe that what we are watching is real .  Think for example of "Jaws" , we all thought the shark was real; my partner has never swum in the sea since......or "Grease" , Olivia newton John made us believe she was 17 and we were back in the 50's ; a couple of my cousins saw the film at least a dozen times at the movies , because it didn't come out on DVD until years later.

Recently watched "William Tell " and "Firebrand " at the movies , both very good , good sets and locations , costumes, etc; and well acted .....we were transported back in time to one possibly true story and one very real story.

Transported, believable, relatable.

Hope: To keep the general feel of the story. It has an understated kind of charm to it that would be lovely to see captured. So that means...

Fear: They don't rely too much on action - action - action! Let the story go at the pace that it needs so that we can experience the atmosphere of the places. I think this ties in with the emotional storytelling versus the more literal that we seem to get from Hollywood now. (I desire more of the former again.)

Really I have a lot of fears that others' have mentioned!