Although this isn't who you're talking about, it's not unlikely that Alex Smith will be available soon. The fact that the Chefs want to cut Smith and start Mahomes next season is perhaps the NFL's worst-kept secret.
Would he be a reasonable option for Denver? Well, he knows the teams in the division as well as any of the other options, probably better. And he'd probably be pretty motivated in those two games against his every year. How much would he cost, and how much has he got left in the tank? Those are the big questions.