From what I understand and have heard, Depp is all about making numerous Pirates movies because Jack Sparrow is his favorite character to play. Also I've heard that Orlando Bloom does not want to make anymore for fear of being typecast (which I think is dumb as hell, because when you think of him you think of Will Turner and Legalus (sp), and thats it... sorry Bloom but elizabethtown is not going to be remembered past this post, stick with the Pirates, its a good thing you've got going for you!).
Anyways, I wouldn't mind seeing sequels without Bloom, its Depp that would push me away from the series. If there is ever a Pirates of the Caribbean movie without Johnny Depp then I don't want to know about it. Depp is Pirates in my mind, thats also the only reason I didn't like the 3rd one as much as the first 2, because as I said before it just didn't seem as if he had as big of a roll as in the first 2 movies.