Jimmy Butler - Miami Heat
The "That will never happen!" crowd is already screaming that from the mountaintop. That goes beyond Butler. Danny Ainge and Pat Riley have a well-documented rivalry dating back to Ainge's days with the Celtics. There's no way they would help each other out.
Except knowing the Heat's uncertain future both overall and with Butler. Plus, if the Jazz's interest in George is legitimate, Butler would serve as a pretty solid selling point knowing his reputation and his talent as a star. There is a scenario where they could work something out, but only if the Heat truly are ready to moveon from Butler.
Even if they're in their mid-30s, Butler and George would be the best wing combination in Jazz history. Pair them up with a stretch-big with the offensive finesse Markkanen has, and Utah would not only project to make the playoffs. They could actually make some noise in the postseason.
Of everyone mentioned here, Butler is the most optimistic target because he's the best player mentioned. He definitely changes Utah's direction as a franchise, but it just might be worth it knowing what he, George, and Markkanen would bring together. Even if the likelihood of him coming is less than zilch.