I wouldn't quit being a fan, but I would definitely be frustrated.
This team sorely needs a true defensive core to build around. Chara isn't that core anymore; he's on his way out. Once he's gone, what do you have left? Krug is a good top 4 pairing player at his best, but I don't know if he's a number one D or not. Nobody here wants to keep Kmiller or McQuaid as anything other than third pairing, and Cmiller and Joe Morrow both apparently can't keep their confidence high enough to stay regularly in the line up. NONE of us want to see aging vets with little left to offer like Liles anymore..
So what defensive core is there to build around, aside from Krug, if Carlo is gone? At least with players like Marchand and Pasta, possibly Spooner and Vatrano, there is some hope for the forwards group. Bergeron's having a crap year but he's not going to fail to produce like this forever. Backes still has some life left in him, and I think Krejci's capable of continuing to garner offensive production as well. The bottom 6 has plenty of potential as it is.
My point in all of this is me wondering, is Landeskog really worth making a defensive core, which has seen some life spring back into it with Carlo's emergence, weaker? Essentially putting it back where it was as it stood last year? Who wants to go BACK to that kind of play? It was hard to watch those games. Rask needs the support in scoring, yes, but having a solid defense also works wonders. You can't sustain winning without out that.