Just finished watching this, it was ok...hate to say it but as far as the flow of the movie and entertainment-wise Black Adam was better the Black Panther.
Tchalla's death dues to "an illness" was a cop out to me.
Another annoyance was missing scenes from the first trailer.
There was really no way to handle the death of Chadwick Boseman in a manner that would make all fans happy about it.
If they did as they've done, by effectively writing him out with dialogue, it will upset some fans that the core character was not recasted. ( Though there are practical considerations here, the MCU overall has burned through A LOT of established actors in their universe and there are a lot of DCEU actors who are too known in their roles there to cross over effectively, who is left in terms of young black male actors established enough to take the role? )
If Coogler and Feige wanted to recast T'Challa, then they risked putting a franchise on an unknown or a possibly fringe actor. A few established actors out there who might fit could avoid the role because if the film bombed, they would be blamed for the franchise dying. This happened to Barry Pepper and Battlefield Earth. He took a lot of the blame for the film failing even though clearly it wasn't his fault. It probably hurt his career very badly.
A "girl power" movie fits into current "modern theme" of the MCU. So Feige would have been criticized and called a bigot if he didn't allow a woman to rise up and become a new Black Panther. Also he'd be called a racist. Someone will say, how in the entire world is that racist if you have a black actor/actress replacing a tragically deceased black actor? Which is a good question. But in today's time, when there is controversy, everyone just gets called a racist now in Hollywood. Someone would go down the production crew list and be upset that more minorities weren't working catering or as cameramen, or whatever. Why would Feige want to deal with any of that?
Since Boseman, again very tragically, had some lead time before he passed on ( i.e. this wasn't a sudden death, clearly Boseman and Feige and Coogler knew this was coming ) , he could have filmed some last scenes that would work as an exit. But many would consider that "ghoulish" or criticize that, i.e. exploiting his death to market the film. Then there was the risk of doing that or a total recast, of having his family and estate complaining and making it a huge scandal in the media.
I don't see a good answer here. I don't see a safe answer. I see Feige taking the "safer-ish" answer given the complex situation. In effect, this is how "new Hollywood" works. Productions are basically held hostage. Make a film this way or avoid this ( and yes, that includes not angering the CCP so a filmed is blocked from release in China) or you'll suffer. The end result is a compromised production and end product.
In any of the variations I listed, keeping it as was made, recasting, or Boseman filming exit scenes, any of it could have worked if there's good writing and you focus on telling a good story. But telling a good story is way down the list of requirements now. First is money, always money. Second is not getting "cancelled". Third is bending the knee to "Woke". Good storytelling is just not a priority over other elements and it makes these valuable IPs suffer for it.
Spoiler: 
