Well it would be tough at contract time for a player to argue that its his teammates that are responsible for his success and contribution and not himself.
Kessel has 10 goals in 38 games this year which puts him on pace for 21.5 (over an 82 game season). Which would be his worst as a Leaf heading into a contract renewal season.
Bozak has been a common denominator throughout, as he has centered Kessel for most of his time here. What has changed is the coach and the system, which is the greater factor effecting Kessel. IMO
If the argument remains Kessel needs better players to be better, than its also logical to suggest that better use of cap space and money would be on acquiring and spending them on those better players to benefit the team more, as simply paying Kessel more money isn't going to change anything. Good players demanding top dollars make player(s) around them better by their presence, not the other way around.
Thus the belief by some that trading Kessel for those player(s) addresses a means to better the team by using him as the asset to acquire them, should be an option worthy of consideration.