Irving and Durant both are leaving the team surely as it seems. They have both wanted their trades as soon as possible. Actually Irving was closer to be traded but the team made a decision and decided to give priority to Durant's trade. I have heard that Miami Heat and Phoenix Suns are the teams Durant want to go now.
Durant going to the Heat would give the Heat a big boost even if they will trade Butler for him.
IMO, I believe that Durant is more clutch and more team player than Butler, so I'm okay with that trade if that will happen.
I don't think that's gonna work for the Heat. I'd rather see the Heat aims to build good back up players that surrounds Jimmy and their young talents. This current Miami Heat roster is actually pretty good and can beat any teams in East during playoffs if they can avoid any injuries with their main rotation.
I would rather see the Heat go after a good Center than trading Jimmy for Durant. That'll only ruin the team's chemistry.