Despite all their faults I love the Walden Media Narnia films and would be thrilled if they included William Moseley and Will Poulter in any upcoming adaptations since they both seem to have a strong affection for Narnia but right now I am going to go way back to the BBC Narnia adaptations and say I'd like to Samuel West make an appearance (in my head I see him as Professor Kirke, Miraz, or Lord Bern) but don't know if that's likely, he seems to mostly take jobs that are filmed in the UK and I am assuming the Netflix Narnia will be on a very grand scale with international filming locations. 

Richard Dempsey still acts too, mostly very small roles but it would be fun to see him involved in even a small way with a new Narnia.

Warwick Davis starred in Walden's PC as Nikabrik and in the BBC versions as Reepicheep and Glimfeather, so it's not out of the question that he might come back as one of the "short" characters in a new adaptation!

To me the best actor EVER in a Narnia adaptation was Tom Baker as Puddleglum in the BBC's SC, but he's a lot older now and I don't know if he takes acting roles any more. Actually, with his deep and easily mysterious-sounding voice, perhaps he could now make a good Professor / older Digory... 

It's an interesting question. I think go ahead, make a cameo if you like, those from Walden films or BBC series, but just not in a wink at the camera way! Subtler ways they might do this could make fun little Easter eggs for those in the know of previous adaptations.

Samuel West could be up for it; he sounded pretty enthusiastic in the two Caspian's 'Talking Beasts' episode. I like him in All Creatures Great And Small and it's fun to know he was Caspian years before. 😀 it would be fun to get the former Pevensies in it from the series, as well. The nostalgia would hit harder. Again, in subtle ways. I'm not sure how well Greta and co. would know this series to bother approaching anyone about it!