Just to be clear, Swen is the director and has made it clear that he personally is done with BG3's development. However just because Swen is done with it and has moved on to the company's next project doesn't mean that the game is done being developed, there is simply now a set team that works on it while they start sketching out their next plan. This is how it was when DOS2 came out, and the game was "finished" and released its Definitive Edition while the writing for BG3 has started.
The point is I wouldn't take Swen starting the early stages of development for whatever comes next as confirmation that they're done with the game. There was a Twitch interview with one of the leads after Patch 5 who said that there will still be free updates and possibly DLC or Expansions (although with how the Epilogue they added basically boils down to "hey the story's not done yet don't go anywhere" I would ere on the side of probably).
