The Jazz have little leverage right now. If the Jazz want to trade Hayward, the team they want to trade him to will need assurances that he will resign. If Hayward doesn't give them that reassurance, the deal will not go through. Nobody is even going to inquire about Hayward if they aren't prepared to pay him the going rate next year. Therefore, every team that wants Hayward now will want him a year or two from now. The difference is that Hayward will be locked down and can't walk away the year after the trade.
The dual problems you had with Kiri is that 1. His game was regressing after signing the big contract. His game was also not really in harmony with DWill and Boozer, which made him a poor fit with the philosophy of the team. 2. There weren't a lot of teams with cap space that could use a piece like AK47. Teams that COULD use him needed to give back their high priced junk in order to afford him, which we weren't interested in.
Hayward has gotten better every year and added something to his game. It is possible he could regress, but it isn't likely. His play style is essential for everything we are trying to do as a team. For the next couple of years there will be many teams with loads of cap space and room to fit high priced players into their payroll. There is almost no real chance of Hayward becoming an albatross outside of injury, due to how damn useful he is in every aspect of the game. Trading him away right now would be pretty idiotic.