I personally hope his children are extracted from his life in the least traumatic way and he continues his downward spiral. Let him find out the hard way hedonism is at best a very brief enjoyment that leads to a hollow, unfulfilling life and a miserable death.
I unironically hope when all this is over Nick and April just run off to Vegas together. Anything that gets them away from the children. I would be surprised if Nick ever initiates a divorce though, which will drive April crazy. But I bet he's terrified that it'll interfere with him getting and being in control of the Trust money for the children, and he doesn't want to pay out money to Kayla as part of a divorce settlement.
I’ve been wondering if Nick convinced Kayla that he would get the kids due to her prescription drug use/abuse, and that’s why she hasn’t taken them and left.
I would bet Nick has been systematically denigrating Kayla for
years. If talking about her "ruined body" is something he's happy to say publicly, imagine the sorts of things he either says, or insinuates, in private. She's in a state of perpetual learned helplessness, exacerbated by drug use, because she's convinced she can't do anything, while Nick reinforces it with the ridiculous "I will be us" mentality.
You can see how she'd feel stuck: Nick's a "lawyer" and his parents are rich, how can she hope to fight them adequately in court? Think of all the dirt Nick will have been filing away to use when needed to intimidate her, too. People think Nick's parents would support her with the children, but it seems more likely that daddy or mommy would instantly turn on her, fight to get custody taken away from her, and back up their Little Prince. Where will she live in the long term? How will she earn money? Easier to just hide away and dissociate.
None of this excuses her actions. She willingly and apparently enthusiastically participated in the degeneracy. As soon as you have children you have an inherent responsibility to protect them from harm, to put their lives first, and their needs above your own. She has failed her duty as a mother. Crying "these are the consequences of our actions" to her eldest son doesn't mean shit when it's accompanied by fuck all change.
I think it's likely both Nick and Kayla are miserable with each other right now, but I'd be surprised if they actually divorce. Would be happy to be wrong though.