I think The Last Battle would be the most challenging to adapt. I was reading up online that one of the reasons why BBC-Mini Series didn't do it because they've thought it was too complex (it may have been at the time than it is now).

I suppose this could be a two-part movie, like Harry Potter and the Deathly Hallows, and The Mocking Jay were.

I do think the difficulty of LB is why they have to put MN before it. Those two stories go together for me.

Here is a concern I have about The Last Battle-

The portrayal of the Calormenes could be stereotyped. There is a challenge for Netflix to do. It is quite easy to typecast them because the upper class society tends to be self-indulgent and look down upon the lower class society. My favorite character Emeth is not like that. I think there is a way to make Emeth stand out from the rest. He can actually be portrayed as sympathetic. As for Rishda, I think there is concern that he might be too over the top. Please no over the top Rishda. I would like for him to be subtle and over the top. Also, I think Emeth can be energetic and sympathetic. Hey, these are characters you're going to remember seeing. So Netflix has a challenge on how to portray the Calormenes.