Because it seems, that Karlach's "good ending"-content is tied to certain Ingame-Stuff/-Locations, which is already removed/deactivated from the Game, we can only hope, that Larian wants to reactivate/re-implement this cutted Content back into the Game...sometimes. But i think, generally this will take a lot more amount of Time and Work, than just Bugfixes or other Fixes for small narrative and "mechanical" issues... But there is still Hope, that Things will come back into the Game, but sometimes next Year, not a few weeks after Release...
