To those saying "Marcille and Toshiro wouldn't let Falin go alone!", You are missing the fact that no one in the party noticed that Falin went back in the dungeon alone. She's too meek to object and insist They go back, so She waited until They were gone to go back on Her own.
So Falin would most likely die at some point, and even if the corpse retrievers or other parties found her and resurrected her, she would not head back and instead keep going after Laios until she dies in some deep place where her corpse won't be found.
It would probably take a while for the party to realize that She's missing and went back in the dungeon alone (If They even realize that she did something so reckless and suicidal, and instead just think she went somewhere else).
Not to mention that They also wouldn't have any clue where to look for her anyway.
I really hope this just Laios being a doomer, because this is really tragic otherwise.
Toshiro would probably give Falin space because of his passive personality, but it's highly unlikely Marcille would leave Falin to her own devices RIGHT after Laios died.
Falin would have to sneak away from Marcille, who until Falin managed to sneak away, would be trying cheer her up, comfort her, and make sure that Falin wouldn't do the obvious,very stupid, and probably fairly common in the DM universe:
"I need to go rescue my loved one/comrad/bestbuddy/etc that died in the dungeon!" - Survivor's Guilt is a hell of a drug.
Once Falin disappeared Marcilie perhaps would try to enlist others, maybe Toshiro would let Marcille join his group, maybe even Chilchuck would still join up because Laios had paid in advance.
I'm pretty sure Marcille would make at least make a short-lived attempt to find Falin, even if alone.
Even if Marcille was successful, I'm thinking Marcille would be more likely to convince Falin to give up and MOURN Laios.
If Marcille was only able to find Falin's remains it might lead to the Black magic ritual again (For Falin, Not Laios) - assuming Toshiro and his group wouldn't stop her.
I guess there is the very vague shot of it becoming a bad end with Marcille and Falin eventually becoming Dungeon Masters in order to "equalize the lifespan of everyone" for Marcille and "Revive my Brother" for Falin with Kabru and the Canaries being their direct obstacles (although the Orcs or Thistle would probably be their end, even if they somehow delved quick enough to avoid the Canaries closing the dungeon and forcing them to leave).
High chance Toshiro or his group would turn on them at some point too.
