It’s possible that a lot of people aren’t clear on this, and assume that a movie starring Margot Robbie without Depp means that he’s out of the franchise entirely.
Either that or they truly don’t believe there should be any Pirates films without Depp.
Details are a bit sketchy at this point, but it appears that the plan is for this Margot Robbie film to be something entirely separate from the previous Pirates of the Caribbean films, while the other project at least theoretically could still include Johnny Depp and Captain Jack Sparrow, though it’s unclear right now if it necessarily will.