I would be very surprised if he reached 40 assists, maybe he reaches 30+30 at his best.
Derek Stepan has only reached 40 assists once, he had 40 assists his best season, and he's a better passer of the puck than Andersson who's more of a goal-scorer.
I also would not be sure he has a 70 point ceiling. Going back to the comparison to Stepan who was our 1C for a few seasons, Stepan has never reached 60 points. He had 3 seasons where he probably would've reached it if he played 82 games, but he didn't.
Is Andersson a better offensive player than Stepan? I'm not sure he is. I would say his points for his ceiling could be closer to what Stepan has put up, but with more goals and less assists. He also might not reach that level, and could be about as good as Hayes is.