I would first ask if Eastern anything is needed in 5e. Are eastern humans or elves any different? Could one just reskin regular MM dragons to fit? I would likely just take the easy/lazy way out and just take a 5e dragon and maybe add a cool power if I needed one.
If the reason is to make a cool monster book to sell, then sure. New monsters are always a good sell like magic items or spells. If there is excitement for a new Oriental Handbook then go ahead and come out with new classes and elements and everything.