Away on a mission seems somewhat hokey to me, no? Idk, we as the audience know that he’s not coming home so it would just seem to cut any dramatic tension.
Instead, I think the storytellers should address T’Challa’s passing head-on & focus the narrative on the legacy of the Black Panther & the King’s impact on each character (keep in mind, before the Investor’s Day announcements, I was very much in the recast camp).
This story will have shades of the first film, now T’Challa instead of T’Chaka, but I think Coogler & co. could use those similarities to strengthen the story rather than detract.