1. A star for a star
Depending on how the Jimmy Butler contract negotiations play out, there’s a scenario in which the Heat could trade Butler without taking a major step back.
If a disagreement on an extension leads to Butler asking out, the Heat could trade Butler to a team for assets that could put their offer for Mitchell over the top.
For instance, if the Cavs demand more draft capital, the Heat could trade Butler to the Philadelphia 76ers for three first-round picks that they could then use to sweeten the deal for Mitchell.
Or, for example, if the Houston Rockets decide to make a play for Butler, the Heat could trade Butler to his hometown for useful players like Dillon Brooks and Steven Adams. The Rockets also own the third overall pick in this draft, multiple future picks, and several young prospects.
A three-team deal that sends Butler out, helps Miami hold onto more of its current group and lands Mitchell could look something like this:
(It's fair to ask if the Cavs would simply swap Mitchell for Butler. Maybe, but then they would be in the same place with Butler as they are with Mitchell -- haggling over an extension. Unless Butler makes it clear to Cavs management that he'd be willing to stay long-term, this isn't an option.)
Of course, all of this is purely hypothetical, but the always-creative Heat front office needs to be planning for every scenario.