This Canucks team has a pretty high floor, as evidenced by them being still in a playoff spot with basically everything going against them this year, but they don't have a high ceiling. That was apparent last year even when everything went right.
The Canucks might as well rebuild if you can't get Pettersson to be a top 15 center in the league. He played like one tonight, but 90% his games in the past calendar year he's been 2C quality and sometimes worse. Still, without elite talent, you can't win.
Sure they have Hughes, but they need at least 1 more star. Anything you trade Pettersson for will be a package of lesser quality players. Even if you think there's 20% chance Pettersson becomes a consistent 90+ point guy again, it's better than the odds you'll be able to trade or acquire one in before Hughes has to decide if he stays or goes.
Find a way to motivate him. Find a way to set him up for success and then hope he gets his groove back.