-Minthara would have two exclusive love scenes one for Act 2 and one for Act 3 regardless of the method you go about recruiting Minthara.
-Depending on the way how you choose to go with Minthara in the end, you 'll get a visceral cinematic scene with the two of you going to/ dealing with Menzoberranzan.
-All bugs and glitches associated with Minthara would be fixed, some tidbits of story elements would be also fixed to avoid contradictions.
-One minor side quest to the feline nature of Minthara and a bone you can pick with her for teasing with (insert player agency) can be both for good or bad reasons, after you mingled with a certain cat of noble vibes.
-Return of one legacy dialogue related to Minthara's pregnancy if Tav/Dark Urge is detected to be a male gender.
-Fix and/or enable a large portion of party banters currently not being played regardless of party composition.
-Have an enforced dialogue scene with Minthara in Act 1 the first time you encounter/ reach her proximity to decide whether you'll sneak and knock her out or outright kill or just choose to dialogue with, an approach that doesn't break the immersion and makes it feel less metagamed.
-Include a large amount of side content exclusive to an evil path of the game, more fleshed out options towards some of the morally bankrupt NPC's you otherwise cant side with in a good path.
Call me crazy but I'm quite content with Baldur's Gate 3 in its current form with just an addition to fix 1000 bugs assocaited with MInthara and have it more fleshed out in tandem with other companions.