Wakanda could be considered and maybe no trade necessary. We act like we know everything about that contract, when the amendments (which likely more effectively define ‘family’) are not public. We assume that BP is in ‘our’ definition of families for either Avengers or FF. But Black Panther may have not been included in either, officially.
We just don’t know.
Given the current popularity of Marvel and Uni’s underutilization of it at IoA, I could see Disney getting more aggressive with characters that may be considered ‘incidental’ at IoA. I think there is an argument that Disney has slowly been eroding those rights thru minor abuses over the last few years.
But I don’t see any official rights trading with Disney for Marvel. Those opportunities for horse trading were missed in the Fox and Hulu negotiations. Maybe after the 3rd park opens or after the Hulu sale closes, but it seems unlikely until then.