He cannot have a title as things stand, because there is no title for him to have. Eugenie's royal style is not heritable (just as Princess Anne's isn't) and there is no other. Unless one of the parents were ennobled with a heritable title - which is what happened to Princess Maragaret's husband.
So that was granted to the Snowdons, offered and declines to the Phillips, and it has not happened for the other female grandchild (Zara) and Lady Louise isn't old enough. Princess Beatrice's husband has an Italian title, so perhaps her DC will inherit that?