He was dressed very informally in this portrait, perhaps allowable given that he was illegitimate royalty, really nobility. He is hard to pinpoint in history, and does have Tudor looks, and a resemblence to his father, defintely. Is there any known portaits of his mother, Bessie Blount or not? I think it would have been unlikely of him to have married his half sister, this never happened in Royal families of the time, although marriages did take place between close relations, even niece and uncle!
But that would have been a bit much.
Anyway, it is possible he might have been made heir, had he lived, and had things happened differently with regard to Jane Seymour giving Henry an heir. It would have been a bit of a last resort though. But perhaps Henry would have done it to ensure the continuation of the Tudor Dynasty.