Idea:
Boston in: Tyler Johnson, Kelly Olynyk, #13 pick and 2020 Phoenix 1st (top 4 protected)
Boston out: Al Horford, Guerschon Yabusele, #20 pick
Miami in: Al Horford, Guerschon Yabusele
Miami out: Goran Dragic, Kelly Olynyk, #13 pick
Phoenix in: Goran Dragic, #20 pick
Phoenix out: Tyler Johnson, 2020 Phoenix 1st (top 4 protected)
Reasoning:
Without Irving and Davis I don't think Boston can contend, so if Horford is interested in Miami I'd let him go. With Johnson and Olynyk we get two teamplayers back who can both shoot and pass. I'm aiming at 2021 free agency, when both contract expire, so I believe we can afford overpaying them till then. We get to move up in the draft (2 picks after another) and get an extra future pick.
Miami is stuck with a huge payroll. With Horford they'd obtain a big man who can play alongside anybody and help them with his veteran presence to make the playoffs. Winslow has been at his best as the main ball handler, so losing Dragic isn't a big deal. Neither is Olynyk with Horford coming in. For the acquisition of Horford they give up #13 pick.
Phoenix needs a point guard. Dragic has been succesful before for the Suns, so if there's no more bad blood it can be a good fit. They get rid of overpaid Johnson and have to give up a future 1st round pick (with light protection), but get a pick (#20) this year as compensation.