Kane has one year remaining (after this season) on a contract that carries a $10,500,000 cap hit and the new General Manager Kyle Davidson made it clear when he took over officially that the Chicago Blackhawks will be entering a rebuild.
At the age of 33, Kane is no spring chicken and if the team is about to enter a rebuild that can be hard for not only Kane who is still preforming at a top level with 78 points in 62 games (103 point pace), but it is also hard for a team to rebuild when they have this kind of star talent as they want to be losing games for a higher pick, not having their star player stealing them wins.
If the Hawks do decide to trade Kane in the offseason he will bring back a very large haul in picks & prospects that could drastically speed up a rebuild. And if his heart truly does want to stay in the city of Chicago, he can always return as a free agent at the end of the season and have the ability to chase another cup elsewhere.