The answer? Replace him with Fred Willard.
Willard, who played Chase's character Pierce Hawthorne in a show-within-a-show that Abed was fantasizing during the cult hit's series premiere in February, is apparently the favorite choice of casting director Tristram Shapeero.
"Who wouldn't love more Fred Willard? He was amazing, and such a gentleman to work with," said Shapeero. "So, who knows? We have to cook something up if there is a Season Five. We can't really say that until we know if there is a Season Five. Then we can have those discussions."
Executive Producer David Guarascio added, "I think we've proven we can just say it's Pierce and move on."
Given the fact that Chase had already exited the series before Willard's episode aired, a number of fans on social media sites expressed variations on that same basic idea: Community exists in a world where it would be perfectly reasonable to replace Chase and have no one except Abed acknowledge the change.