The Grand Theft Auto series is defined by its satirical take on America in different time periods. How are they going to do that in any of the places you mentioned? Satire only works if the core audience understands the premise.
The vast majority of sales for the GTA series are in the U.S. -- GTA:V will almost certainly be in an American city. The only exception would be if they picked a period in time in a specific city that is extremely well-known in popular culture. I can't think of anything in the above-mentioned cities that qualifies. I also think Tokyo, for instance, is out, unless Rockstar feels comfortable having all of the main characters speak English.
New York was an excellent setting because it's extremely well-known, a common setting for movies and TV shows seen across the Western world, and it's very diverse as well.
If Rockstar is indeed doing Hollywood (though it would be truly surprising if it weren't at least all of L.A., b/c Hollywood is too small), then it may not be 2010 Hollywood -- it may be set in the 1950's, for instance, because of the furor over McCarthyism and allegations of communists working at Hollywood studios. Plus, 1950's faux American wholesomeness (see, e.g., Leave it to Beaver) would be a great satirical target.