Setting everything else aside, can you imagine being the poor actor actually asked to play T'Challa in Black Panther 2? They'd be George Lazenby at *best*. Some of the decision to go with the story they did might well have been "Nobody good enough to do the role, is going to want to touch the role".
In George Lazenby's case, he
literally could not act ,
The guy was a model.
The Bond producer's gave him the role because he nailed a stunt fight scene in a screentest.
Had they cast someone who was charismatic and could actually act , the response to OHMSS would have been quite a different.
Who knows if they would have been considered as good as Connery, but it's likely they wouldn't have been pilloried like Lazenby was.
As far as BP goes, yeah, there may have been a " Nobody good enough to do the role" scenario, but there are a number of other scenarios such as:
They pick someone who's met with skepticism, but wins the audience over
Someone who everyone thinks is a great recast
Someone who , while not considered as good as Chadwick , is accepted never the less
etc.
The problem is, what could come up with tons of " What if" scenarios, positive or negative, because it never happed to begin with.
At the same time , we can't say X or Y would have definitively happened because the decision was made not to recast the part.
It would be speculation as to how the audience would respond to the recasting of T'Challa and then to how they would respond had they seen the actor's performance.
At this point, there's not gonna be a definitive answer to the question of what would have happened since Marvel Studios stance is that they won't recast the part.