They probably wouldn't use the original actors. Or if they did, it would be just be using their voices. I'm guessing it would be rides/lands set in the recognizable areas of middle earth. A battle against/escape from Sauron and the Nazgul wouldn't need any original actors anyway. Sprinkle in some random elves, dwarves, and hobbits, and it's all good.
The last time we got a land based off an extremely popular franchise that didn't feature the characters people liked we got Galaxy's Edge...I would be ecstatic to experience second breakfast at the Shire, but I also want Frodo and the Fellowship to thank me at the end of a ride!