Using this digital image of Washington at 53, the researchers first will use computer software to "age" him to what he looked like as a 57-year-old. Similar techniques are now used to portray the current appearance of children who have been missing for years.
Q : I think "as a 57-year-old" modifies "what". Right?
The adverbial 'like what' complements 'looked', and is therefore necessary. (The as-phrase, in contrast, is merely a modifier, and therefore optional).