Ponyo 2

It is known that originally Miyazaki wanted to make a sequel to Ponyo instead of The Wind Rises. As much as I love The Wind Rises, I can't help but wonder what Ponyo 2 would have been about.

I imagine we would see Ponyo a bit older and find her struggling to fully adapt to the human world. Maybe see her going back to the ocean to visit her parents and causing some kind of issue. Does anyone else have any ideas where Miyazaki might have gone with a sequel? That would be the one question I would love to ask him.