*shrug*
I get the joke. It's clever, in its own abstract way. The poster shouldn't say that Depp is going to play Godot, though. He could easily be one of the two that are waiting. Maybe he and Bonham Carter are sitting around waiting for a Tim Burton adaptation that isn't several notches off of the 'needless' meter. They really would be waiting forever for that one, or, at least, present day cinema suggests that they would be.
The idea that Burton would give Depp a role that isn't supposed to appear, and then shoehorn it in is perfectly valid, though, so I suppose it's an acceptable interpretation. (Godot being an absurdist play, I believe there should be many different interpretations of this drawing, and therefore challenge people to come up with more).
Interesting work, my friends. Next time make some mention of The Blacks, though. Genet's works generally offer a little more in the way of the fixed-yet-open-interpretation that really good absurdist theater needs than Beckett's do.