Cozart is definately going to start at short, he played well in his first full season last year. He's a decent hitter, fine defender, and still a fairly young player who I'm sure the Reds expect to improve next year.
The Reds organization seems to be firmly of the opinion that Hamilton is still a raw player. Even with an excellent Spring, no way IMO will Hamilton push Cozart, and I think the Reds want to develop Hamilton as a CF anyway. I'd be very surprised to see him up from the minors for any real length of time this year. Of course, injury can always play a factor.