Tit for tat. It’s only fair that Bill Murray’s replacement should be Chevy Chase after Murray replaced Chase on Saturday Night Live. They’ve since made up (probably?), but Murray and Chase famously got in a fistfight when the departed Chase returned to host SNL after his film career took off. So give the role to Chase, but let Murray hit him hard in the stomach first. Street rules.
This is what he secretly wants. You just know it. It would be pretty difficult to pull off when the crew realizes they never see Dan Aykroyd and Bill Murray in the same place, but with a little Mrs. Doubtfire-esque planning, it could be totally doable.
If Murray himself won’t do it, they might as well keep it in the family. Joel or Brian Murray would be sound picks for the replacement. There’s the physical resemblance, the same dry wit, and neither are Jim Belushi. It’s almost too perfect.