I think it makes sense for Kamala to have an important role in the storyline where she was made a mutant. Whatever you think of the actual retcon, the genie is out of the bottle at this point so its a good idea to do something important with the character. As far as her taking the Captain Krakoa mantle, it's obvious she's using it as a tribute to Scott. It was a role made for him to cover up his death, and it wouldn't make any sense for Kamala to use the Cyclops name. Also I'm sure Doug's role in this event was decided a while ago.