A bit of speculation here (probably far-fetched speculation).  What if Greta Gerwig was doing some casting for the both of the first two Narnian films?  One casting call listed two boys and one girl being sought for roles in the movie - what if this was Digory, Polly and a lead for the 2nd movie?

If they need to begin casting a boy for the 2nd movie early, then it would seem likely that it is a demanding role that requires extra time to find the right child actor.  (My guess would be a boy who could play two characters with different personalities convincingly - i.e. possibly playing identical twins.)  The question I would have is which boy is playing Digory Kirke and which is playing Shasta & Corin?

I could see the boy with the Indian father being Digory as several people have pointed out the references in the Magician's Nephew to Digory's father being in India.  I find it intriguing to entertain the possibly that King Lune could look Indian.

Given that in the Narnian time line that C S Lewis gave to Walter Hooper ( https://narnia.fandom.com/wiki/Narnian_timeline) the Calormenes are descended from the people of Archenland and the people of Archenland are descended from King Frank and Queen Helen, it would make sense for the same racial diversity to be present in all three kingdoms.  I thought this could be quite cool.

Obviously if this was the case, then the first two movies would be The Magician's Nephew, followed by The Horse and His Boy.  From there, I would guess they would release the other stories with the Pevensies, Eustace and Jill in order (Published order and Chronological order as it becomes the same thing at that point).

Well, at least we know The Magician's Nephew is going to be first (which I think it will be nice for a change, because both the BBC TV series and the Walden films started with The Lion, The Witch, And The Wardrobe. So I think it kind of makes sense to start with something different). Then of course, depending on how well it does, it will be interesting to see where they'll go from there. It's possible it could go chronologically,. But then who knows? It would be nice to a see a fresh take on the well known story The Lion, The Witch, And The Wardrobe (if that is to be followed The Magician's Nephew) but then who knows? We'll just have to wait and see how well The Magician's Nephew does.