Is it possible that both extremes are kind of wrong?
Ghost is a unique and fantastic offensive weapon on the blueline whose defense is underrated but hardly elite. He has a terrific contract and could be a big piece going forward. That's all absolutely true. But it doesn't mean he's an absolute necessity and couldn't be moved in a deal that improved the team.
For all the worries about the defense, it's probably in better shape going forward than most around the league, even if the cupboard isn't as stocked as it once was. It isn't that they're lacking good young defensemen, they have more of those than probably 80% of the league. It's that they're lacking veterans who don't suck. They need to get back to drafting blue liners, but should also be looking to acquire at least one actual good experienced defender. Scrape out the duds (Folin/MacDonald) move one or both of Gudas and Hagg, let Morin and Myers graduate, go find Provorov a real veteran partner.
I wouldn't have any interest at all in trading Ghost for a forward, because I don't think that's a position of need. But as excellent as he is, I also think he's probably less essential than some believe, despite his contract and scoring potential. He should be here for a long time unless you can find some sort of steal on a top pairing defender.