We have seen the decline of Brent Seabrook and Duncan Keith rather quickly over the last few seasons. While I still believe Keith can be a game-changing force on the ice, he has dropped off from his inhuman years of playing over half of the game. Every player reaches the tail end of their career at some point. Even Jaromir Jagr could not play in the NHL forever, age is going to catch up to everyone.
There is no reason that Blackhawks fans can believe any different for Jonathan Toews and Patrick Kane, and honestly, the sad realization is that we are going to need to rely on someone else besides Kane and Toews rather soon.