It's maybe worth mentioning that we went through this exact same "debate" earlier on with Gallagher. After his ELC he signed a 6 year deal, and year 2 was a down year with 29 points in 64 games, after having 40 in 53 the year before. And all the same things were being said about how long term deal for a player his size and style was a mistake because he's always going to be injured and will be out of the league within a couple years, won't be able to adjust his game because he lacks skill, etc... Yes he's older now and the contract is for a larger % of the cap, but people have been saying and doubting Gallagher all his life, so I wouldn't be too quick to bet against him rebounding and being a useful player. Gionta was another guy who was supposedly finished due to injuries when he left MTL and was much older, yet he still had some decent seasons in Buffalo. Markov came back from injuries and was still a top D-man. In the end there's no need to rush a decision about him.
If Gallagher can rebound into being a 20 goal 35-40 point player he won't be worth his salary but he also won't be worth trading for another team's garbage contract either. And as mentioned before, his contract is buyout friendly, so the worst case isn't that bad a situation anyways. Now if there's a team that thinks Gallagher is a playoff warrior and is willing to give up something of value then yeah take it and run, there's just no need to worry about him or rush to do something. It's not a disaster, it's not an anchor, it's not going to stop us from doing anything we will want to do short or long term.