I think he can wait for CivX at this point. Also, Jeanne d'Arc was nineteen at the time of her death, sixteen when she became the "Maid of Orléans."Napoleon can sit Civ6 out and come back for Civ7/8.
I would like Louis XIV to get a voiced appearance, not necessarily as an alt leader for France in Civ6, but in a future game.
Joan of Arc, I won't accept as French leader. I feel bad for her, she was like 16 when she got burned to death, but I don't think she qualifies as a French Civ leader.