User blog comment:J Fan/Pirates 5 - Sequel News Rundown/@comment-12320611-20130822171513/@comment-1984959-20130822183819

Personally, I would say it's speculation because Geoffrey Rush was interviewed about any updates as well as expressing interest coming back. So technically, it isn't a rumor per say as Rush has a very strong chance in returning, as noted by this interview with Jerry Bruckheimer(which also has an audio clip):
 * But for example, was Captain Barbossa always going to be part of the new story?
 * Bruckheimer: You know the way Terry works, and Ted and us is that we start writing out 3×5 cards on things we would like to see in the movie and we put it up on a big board. And Barbossa was always one that came up on the board, because he’s such a great actor, Geoffrey (Rush) and we wanted to bring him back. He’s so much fun to watch. The decisions are made like that.

Having said all that, I will say we have to brace ourselves for any possibility - good or bad. Barbossa's return ultimately depends on if the character is part of the story and of course on if Geoffrey Rush himself is still has interest or not. Of course things will be answered over time.