I prefer Green to Hayward, personally. Of course, I'd be happy to have both. The C's should be able to absorb Hayward's 1st year salary next year with their trade exception (unless he's getting ridiculously overpaid, in which case, no thanks). All that matters is draft compensation. Other players going to Utah are not necessary, from a salary cap perspective, in order for a S&T for Hayward. Accordingly, only players that Utah actually wants need to be included. Salary filler is unnecessary.
I certainly think it's possible that Hayward ends up here, but I think some of that will depend on the draft. Hayward isn't as necessary on a team with Jabari Parker, for instance. It's a deep draft in general, but it's particularly deep at the small forward position. If we get one of Wiggins, Parker, Saric, or Robinson III (who is going to blow up this year, mark my words), I see no reason to have Hayward competing for those minutes. Keep Green, and re-evaluate when his contract is done.