I think bringing Viconia or Sarevok into the party in any respect would be the worst thing Larian xould do. Its already clear thag Larian included them in this game without any real point to their inclusion. Unlike Jaheira and to a lesser extent Minsc, they have no point in the story, not one that is worthy of their status and past in the series. We've already seen with Halsin what happens when they try and force in characters for fan demand. The best thing to do would be to remove them outright. Forcing characters who don't ha a purpose in a story to occupy even more space within that story is a recipe for disappointment.

Also I don't for a moment think wotc had anything to do with this. Clearly Larian was not meaningfully beholden to anything.