Instead of a DLC, I'd like it if they just tidied up what is already there: Maybe open the Upper City, make use of all the blackmail material you can find, give everyone an opportunity to send Karlach to Avernus, give Gale a end-cut-scene for his quest (not that weird Mystra conversation you shouldn't be able to witness), give Wyll something to do, fix Minthara's bugs, make that whole Halsin situation less jarring, give the guy something to do in Act3 (apart from being bait), fix the player dialogue in some cases, maybe the dock scene too .... this sort of thing.
