Demko is only a season removed from missing a sizable amount of time due to injuries, and promptly playing awful as he attempted to recover while clearly brought back too early. DeSmith is basically insurance, especially when none of our goalie prospects have shown they're ready for the NHL quite yet.
I'd be stunned if the Canucks moved DeSmith barring an absolutely stupid offer. If say, New Jersey wanted to throw out their 1st, which DeSmith is definitely not worth despite his stellar season so far, then we'd probably make that work. But that's fantasy. Nobody is giving up that kind of value for a career backup on an expiring deal.
My hope is he doesn't ask for much of a raise and we get to bring him back next season.