Toronto doesn't work, but Montreal makes too much sense. Seeing him in a Canadiens jersey would be putrid.
The Rangers are another destination that might make sense since they were apparently a team he was willing to go to before (unless I am misremembering), and they are willing to move anybody. If the Rangers add Karlsson and Miller, that is a pretty big change in a short period of time. With how negative the players seem to be on Drury, I'd imagine that he might not waive to go there.
I can't help but feel there is a chance that he will end up back here. The fact that we wanted Klingberg shows that we might feel the need to add some offense from the backend. We need help scoring. Alfredsson is on the coaching staff. If he can fit into whatever the room is now, a motivated Karlsson in a bit more of a sheltered role could dramatically improve the team. But it would come down to whether Pittsburgh is willing to heavily retain and take back contracts. I don't think Norris for Karlsson makes us better right now. Amadio+Forsberg for Karlsson (w/ retention) and a waiver exempt 3rd string goalie might. I doubt Karlsson will cost much in terms of actual assets, they won't be able to get a market going for him. Dumping half of the contract will be the return for them.