They've gotta go with Brooklyn - it would ensure a rabid following amongst Brooklynites, and to call them the New York Nets would doom them to forever being "that other New York team".
Plus, (and maybe this is just the former Brooklynite in me), I have to think that there would be more merchandising potential in the Brooklyn name. New York already has, what, seven other pro sports teams?
-MHM, winner of the 2000 Throwdown in Christmastown.
I wouldn't be surprised if someone down the line brought the NBA in court about this; not as much for the 19 age limit, but because it sounds as though foriegn born players will be able to get in 18 and it's an unfair double standard.