I mean, I'll just be blunt. Outside of any agendas...
If they announced Shuri is taking over for T'challa, then BP2 immediately becomes just another MCU movie to me. Which means I"ll be there opening day, I'll buy the home media purchase... but you won't see be at the theater 4x (unless it was magically epic) and I ain't gonna start buying shirts with Shuri on it. Or hang Shuri posters in the gym. It just won't happen.
I'm in this for T'challa, the Black Panther. the BP mythos are his. HE is the Black Panther.
Okoye, Shuri, Nakia, M'baku, W'kabi, and such are cool, great supporting character. Awesome supporting characters. Really elevated the first solo.
But they are just that to me... support.
BP2 without T'challa is like a step above Eternals for me in regards to excitement. I'd be much more excited about Thor 4, Shang, DS2, Blade, GoG3, and maybe even CM2.
Just being honest. I've always said i am a T'challa fan though.