This is actually a frustrating question. Because of the asinine decision to lock the default Hawke appearance down many PC gamers, including myself, downloaded a mod which allowed character creation using the default Hawke as a base. That way we could, for example, remove that stupid nose blood swipe, change eye color and hairstyles, thin the face, ect. I personally loved changing hair between Acts; making an evolving character. Default in Act 1; tight ponytail in Act 2; loose ponytail in Act 3. Reflecting the position, so to speak.
So it depends on what Inquisition does. Almost certainly it will follow DA2 and not allow any modification to the default appearance; but knowing that for certain would be very helpful so we can choose Default Appearance in the Keep before playing however many hours and being slammed with a butt-ugly Hawke creation process.