The more I think about it, the more I'm conviced it's already done, quests are developed, story is already written and dialogues are recorded. And we'll have the rest of the storyline for companions that are related to Baldur's Gate like Astarion and Karlach.
Bloody hope you're right. The best case scenario for us right now, I think.
And hey, considering those people who had to stop playing upon learning that the endings are underwhelming, and also those like me who have a duckling syndrome about their first character and only truly replay RPGs once there's new content presented for those characters (especially if I was mad about it), plus the "I wait till all the content is fixed and added before buying" players... I mean, that's not a lot, but Larian would definitely be bringing back (or keeping) a chunk of people if they released the, uh, "Extended Cut" of the ending/Act 3 Win-win!