No matter who you trade in terms of core player, you're gonna lose the trade probably and it's gonna suck. That doesn't mean they can't be a better team for it. I kind of see it like when Boston gave up Joe Thornton for scraps and ended up being a contender for a long time. When Colorado had to ditch Duchene, they turned it around, I think we know what happened. Just 2 examples that jump out to me, there are probably other ones.
This isn't to say it can't completely blow up in the Leafs face if they make a franchise defining trade, but I hope whoever makes that trade isn't someone like Brian Burke or Chuck Fletcher.