If Sam and Bucky can get a D+ show as the legacy of Cap, I don't see why Shuri can't get that while T'Challas story plays out in the MCU. It's still shared, and these people would get MORE Shuri more often, less wait time in between seasons of its a hit, and more development that you can get with movies.
The Only reason I see that these folks wouldn't like it is because they can't say that Shuri is the SOLE holder of the franchise, they can't say she is THE black panther. but if they actually cared about representation then this would be a great compromise, especially given Shuri would eventually segueway I to the mcu and take over after T'Challas story is told (I'm hoping that of recast, the actor gets a 3 solo movie deal as it's only fair) and he moves on.
For domestic, T'Challas solo movie grossed more than Cap, Tony, and thors first two movies combined (I'm going to go out on a limb and say it's grossed more than every marvel movie and it's sequel domestic) I don't think Disney is dumb enough to go "You know, people went apr **** whenever T'Challa show's up, let's kill him off and push Shuri instead".