I think his brain is fried more than ralph's at this point. I think the time frame for another relapse, or at least a stream relapse, is months. I'm not entirely convinced he even quit his menagerie of drugs since getting home.
I can't believe I am going to defend Ralph...
Despite what he says, and despite his deplorable behaviour suggests, Ralph clearly was shook by Pantsu leaving with Rozy. Enough that it sobered him up - minus the odd stumble here and there - for the longest period we've ever seen. Maybe even longer than when was in prison.
Point is, even in his xanny and Modelo rotted brain folds, he was able to care enough about something to realise he needed to change. I dare say what happened to Rekeita was in many ways worse than what happened to Ralph, and Ralph was far more isolated than Nick, and yet it was the fat retarded redneck loner that tried to fight his addictions.
It's sometimes said that smart addicts are often the hardest to get through to, their ability to create explanations, to deny and deflect is far better than a simpleton. Nick is very good at employing this sort of rhetoric in general, so that alone leads me to believe he's got a poor prognosis.
Based on what the general understanding of Nick is, I doubt he will ever change. He seems to have very little will power, and even less interest in hard work. People like to blame parents, and sure it's clear they enabled him, but realistically he would probably just have ended up as some annoying bum know it all who thinks he's the smartest guy in the room, despite being a fry cook or something. Completely wasted talent, and a repugnant attitude.