I don't know DPC personally, so maybe he really is just making games to torture players at the end (hey, we all have our fetishes) but I seriously doubt this game will end with the same grimdark manner as AL. For one thing AL was way, way darker from the beginning of the game (the MC almost get killed and one of the love interest is getting physically abused). Nothing in BaDIK has risen beyond the level of melodrama so far IMO.
I'm not saying the ending of AL didn't come out of left field or was darker than even those plot points listed above merrited, but if you look back at the AL thread people were predicting that it would end badly way before the fire update. The signs were there. I don't think you can say the same about BaDIK in good faith given what's happened in the story so far*.
Also, and admittedly this is a bit of a meta reason, but everyone is on the look out for the shock ending now. The same magic trick isn't as effective twice and I doubt DPC wants to be considered a hack.
There could very well be a sad ending for BaDIK in some of the paths but I really do think it will be consistent with the game at large.
*I reserve the right to completely disavow this comment if it turns out Bella is hiding bodies behing the locked door in the next update.
Signs of a dark twist exist in this game too and there are characters who, whether deliberately or inadvertently, could bring about the demise of another character.
Quinn is the most obvious choice as her actions could catch someone in a potentially literal crossfire or it could happen to her. Maya's Dad is someone who could potentially harm either her or Josy if he is extreme enough in his bigotry that he would rather murder either one than see his daughter be gay. Tommy also has the potential to go a bit psycho as well as he's an impulsive drug addict whose world is somewhat crumbling around him as his way of life with the DIKs is changing in a way he doesn't like and he feels Quinn has "betrayed" him, so he could go a bit off-the-rails in a way that leads to tragic results.
Ultimately, I hope nothing fatal will befall any character in this game, but there are some signs that things could go very bad.
I completely understand where you are coming from with the criticism and I pretty much I agree that for the story we were being told everything happened suddenly, however I felt that AL did some things right with the dark parts. Sometimes, or rather often, we don't see the dark shit coming in our lives. People die unexpectedly without a chance to mend fences or someone else takes an argument too far.
In the end I felt like the darkness at the end of AL was too much, it piled up too many horrible things and ruined the overall narrative of the game, and, the worst part is it tainted the memories people have of the game. When people talk about the game the focus is on the dark ending. I don't know that I've heard anyone else talk about a single aspect of the game other than the darkness and how it was too dark.
My hope for this game is that DPC has learned from AL and will write a story that isn't as dark but has some gray moments. And that we get enough light moments that people will remember the game for versus whatever twists are coming. Essentially a balanced narrative that perhaps tilts towards the light a bit more. Especially considering how dark our real world is now.
Well, as I said, if they don't feel they have anything to learn, then they could very well go in this direction again if it's what they want to do. It would be something of a "one-trick-pony" move to do this and that's why I'd hope they won't do it again, but it is still something of a possibility.