bkev said:

WB doesn't have the best record with celebrity cameos being retained (will we ever see The Addams Family or Laurel & Hardy on The New Scooby-Doo Movies outside of syndication?), but given that this is a much more high-profile release than my example I can see them shelling out the cash.

The thing with the L&H episode could be related to the fact that Larry Harmon owned the rights to the likenesses of Stan and Ollie (as absurd as that sounds). Now that Mr. Harmon is dead, I have no idea who owns the right to the characters, if anybody.