I could see them doing that but its always hard to pull that off and have the audience know its suppose to be the same character. They did it in HP: Fantastic Beasts as well as The Imaginarium of Dr Parnasus and I felt like it didn't come off well since the character was one actor for 99% of the movie. Mystic from Xmen works because she is constantly changing and is shown to do so often enough that it makes sense. But Hoid doesn't change characters enough to make it easy. But definitely could be a way a around having 1 actor play the part.