As far as I know, King is still projected as a late-first or early-second round draft pick. If Hyde were traded, I doubt you'd get a first or second round draft pick in return. Therefore, I'd say most NFL analysts would take King in this situation, and I'm inclined to agree with them.
How many times are defensive backs busts in the NFL? It certainly isn't as much of a boom-or-bust position as QB. I think King is a pretty safe bet to be at least an above average defensive back and one of the main selling points for drafting him is that he has a very high floor, but his ceiling is questionable.