I think the main reason the Jazz traded Deron Williams was not because they feared he'd leave in free agency, but because they didn't want to give him a $100M 4-year max contract he was seeking. That turned out to be one of the worst contracts in the league, and I think the Jazz FO could see that coming. The rift with Sloan and the fear that DWill would leave as a free agent certainly were factors that contributed, but it was a smart-money move, imo. If the Jazz trade Hayward, it will be because they don't want to max him, and they'll choose to sell high instead.
It's a simple question: Regardless of whether Hayward wants to stay in Utah, do you want to max Hayward at $25M/year under the rising cap? Maybe he's one of our top 3 guys, so the answer is unequivocally yes, but that will be the question the Jazz will be asking themselves. Star players on rookie deals who can be extended are really, really valuable commodities.
Hayward is pretty clearly a second-tier star. He's the Joe Johnson, the Shawn Marion, etc. He'll get a max contract from someone, but will it be the Jazz?