Putting Storm and Black Panther together again is probably a bad start as far as some readers are concerned. And really, how many Black Panther books did Marvel think the market would carry?!
Regardless, this is sad. Is Marvel right about diversity and social issues suddenly becoming sales killers? That's a pretty shitty position for us to be in.
I question whether the issue is "diversity & social issues" as it is "how it's being presented", especially in a situation like this where popular characters couldn't even save a book.