Kenan Thompson will set a record next season for longest running cast member when he enters his 15th season on the show. Even though number 15 will be a record it still seems like Kenan is far from done working on SNL. To me it seems like he could possibly go for 20 seasons. I still think he has a good 5-6 seasons left in him. And even though many cast members chose to leave after a certain amount of time there is no rule that you must leave.