According to Cinema Today, US Media has been reporting that Miyazaki Hayao
is developing a sequel to Porco Rosso
based on an interview released in Cut magazine September issue. Although Miyazaki did mention the outline of the sequel, he continued "I realized that it wouldn't work. (laugh) It would be fortunate if I had a chance to produce it easily, but that's already a pastime. (no longer a serious work.)"
Miyazaki said he wants to depict a forward-looking boy in his next work. "But I can't assure you anything now. Yet, the protagonist will be a girl again."
Source: Cinema Today