I'd say that the inclusion of Cosby is pretty much essential. As Patrick said back in October, when news of the project broke, the names attached include D.L. Hughley, Paul Mooney, Tommy Davidson, Reynaldo Ray, Marla Gibbs, Eddie Griffin, and Katt Williams. THR also lists Chris Rock, Steve Harvey, and George Wallace. Some of these funny people are great, influential, and immensely memorable comic names. Some are not so much. But including any of these is incomplete without Cosby, a man who has made a huge name for himself in comedy on stage, film, and televisions for many years.
Looking at the list above, it's definitely male-centric and missing a few big male and female names. Unfortunately, IMDb says that it is already in post-production. But if the film was in your hands, who would you add?