This could be great for KC, or maybe just okay... I guess it depends on how you view the big picture. That salary does take up a huge amount of the cap for a long time.
We all know there are no guarantees. I'm thinking about how some of the past stellar QB's never quite sustained their success in terms of SB appearances. Dan Marino is a prime examnple. He made it to the SB (and lost) in his second year in the league. Things looked really good for his future. As fantastic as he was throughout his career, he never made it to the Super Bowel again, not even once.
There are other greats who did win one SB, but never again:
Johnny Unitas
Steve Young
Brett Favre
Let's not forget active QB's who are still in the hunt for their second SB win, but whose windows may be starting to close. Let's not forget that Mahomes now stands in the way:
Drew Brees
Aaron Rodgers
Russell Wilson
Of course KC had to secure Mahomes long term, no doubt, and I wish him all the success for his career. But in the NFL landscape, things always change. It will be interesting to see how his career in KC plays out. Will the next great QB emerge on the scene and start to stand in Mahomes' way, as he now does for the above QB's?
I love this sport!