Here's what's going to happen:
-No major expansions to BG3. There will be small additions here and there like new armor sets and items, and potentially associated small quests.
-No BG4. No more DND games.
-DOS3 confirmed.
-Larian lays off at least 25 members of their 400-strong staff.
That's a very terrible outlook after the game when all signs point to becoming a massive success and Swen has openly said within the past week or so that WotC are VERY happy with BG3. So I don't see why they'd downsize and give up on D&D.