That's a very interesting thought! I hadn't considered that before. Given that we probably won't see The Last Battle for several years, there's a good chance that CGI will be advanced and cheap enough for the filmmakers to do this. This could be especially helpful in aging or de-aging characters like Digory, Polly, Shasta, Aravis, et cetera. I would only want them to do it if they could make them look 100% realistic and believable, though.

The garden scene in LB is a scene I have long been hoping will make it to the film (if LB will ever be made into a film). I think it would be really cool if they gave all the actors cameos so we could see them all together. Something like a REALLY big Narnia get together. There are so many characters from each of the books that I really like and I think it would be so amazing if they could get them all together for one last time before we say goodbye to Narnia for good (that is of course if the film is ever made, which I am hoping against hope it will be)

Part of the reason I was thinking about the garden scene was this
graphic (or else I made it because of thinking about it).

As more of the movies are made, the characters can be replaced by the "real" actors, but for now one has to just imagine who they will find. It might be fun, but there's not much use in guessing who will be Polly and Digory right now, because MN is still so far away, never mind LB, and the actors for those parts are too young. That's a funny thought

They can't cut that scene! :C For me, The Last Battle carries a message of hope and that things will be all right in the end. Seeing Lucy and Tumnus reunited in the afterlife would provide a way for things to come full circle. Our first experience in Narnia is with Lucy and Tumnus. It makes a lot of sense to me, then, that it should also be our last. (Another reason I like chronological order, actually...)