The IMDB entry that had the rumor listed has vanished, and it was supposedly a young Captain Jack for this season, not the anniversary, iirc. I'm still holding out hope for JB as Jack in the anniversary ep. He has made it very clear he'd like to go back, and Moffat's made vague statements that are similar. I guess we'll see what, if anything, comes of it, or if "I could go to all Jack's stag parties in one night" is the last the Doctor has to say about him.