Laezel died in my playthrough and Astarion was sent away after the bite incident. So I cant speak for them.
But Karlach has stuff. Wyll has stuff. Gale has stuff.
And yes Shadowheart has stuff. But does she have that much? Nothing much other than the temple of Shar, or anything that ties into it.
Lots of Wyll and Mizora scenes. Karlach has her own thing with the paladins and then fixing the heart. Which yes , is inconclusive like everyone elses story. And for the record, I also want more Karlach and Wyll. But it is bigger than them. And I feel like we will be more succesfull appealing to the fact that the entirety of the last 3rd of the plot is not done.
I have read people who said the upper city was mentioned two weeks before launch. And it is gone from the game?? The epilogue was mentioned to be 20 min ish. And it is gone from the game? It looks like it was here all the stories would conclude. If we get that, maybe everyone gets what they want.
But that is just me. Thinking.