There is a sorta cameo of Kowloon in the Anime "Ghost in the shell #11" a slum which the immigrants have been forced into, not only stylistically resembles the walled city, but is complemented with airlines coming in low overhead .
Very similar in style to the famous WCK. Behold the also famous Chungking Mansions in Hong Kong:
c/o Mindtwist at Panoramio
Maybe that's where many of the former residents moved to. Hong Kong's architecture seems to be the inspiration for many anime, aside from Tokyo and other cities in Japan.