While I agree with you ideally, when examining this pragmatically and realistically.... going the Shuri route is the safest way to appease the public and not piss general movie-goers off.
Only a tiny group of comic fans really know the significance and potential of T'Challa from the comics.
General movie goers would support a Woke Black Female taking on the role if the media campaigns for it and backs it up. I can't see Disney shying away from repositioning this as another 'female empowerment' franchise, as there was some groundwork for that in the first film.
It's also the safest way possible to introduce a Black Female-led franchise into the MCU, because the brand is already established. The film is already a guaranteed billion, so they can risk having Letitia Wright be the new face of the franchise.
I'm not so sure that replacing T'Challa with Shuri is a safer route than recasting the role if we're talking about the general audience. The general audience connection was with T'Challa as Black Panther not Shuri.
T'Challa is the icon in the Black community, and that's regardless of the fact that the mantle has been past down to other characters.
Yes, people who saw Black Panther will likely remember her character, but in terms of the person the general audience identifies and accepts as Black Panther, that's T'Challa.
Even though comic book fans accept the idea of other characters inheriting mantles, that's not necessarily the same with the GA as a whole.
The first BP has gone far beyond comic fans who know about Shuri taking the mantle.
The film plays, and has had an impact on so many levels that alot of comic book fans themselves don't understand or fully appreciate.
While it may be a case of just putting another character in the suit to comic fans, that doesn't mean that idea will automatically be met with universal praise and acceptance by the general audience , including segments of the GA who's infinity to T'Challa and BP goes far deeper than what's on the surface.
So I don't think its as easy or safe to just give the mantle to Shuri as alot of comics fans think it is , if we're talking about the General Audience.
I think a recast , assuming its good, is a safer bet because at least you're still dealing with the same character audiences know ,and identify with ,than it is to give the mantle to a supporting character who audiences may remember, but is not the cultural icon who's been an inspiration worldwide.