I stone cold guarantee their writing will go steeply downhill if they do another DOS game. A big part of why it improved so much was them being brutally beaten by feedback from D&D/BG fans into not indulging their worst, most edgelord/grimdark tendencies.
The moment DOS goes back on the menu it'll be wall to wall edgelord girmdarkery grey choices again. And because Swen loves that vibe he'll ensure they triple down on it even if some of the team push back.
Also DOS2 has possibly the worst combat system of any major CRPG, uniquely combining the worst aspect of perversely designed TT skirmish games, MMORPG-style constant equipment grind (a staggeringly stupid decision) and forced combat encounters or you fell hugely behind XP wise.
Really I think being forced to work with D&D and the FR has given them constraints which have improved them significantly and if they get off that leash with as much money as they have they're just going to go feral.
I'm not saying no one will love the grimdark "every party member is a psychopath" mess that plays like a terrible turn based MMO that they'll make but damn.