@ajuperma
Not necessarily. Britain, a (relatively) tiny country densely populated has dozens of distinctive dialects and accents. London which can be compared to NYC as a global metropolis still has characteristic accents which differ along geographical, ethnic and social lines.
Now, as The Coq wondered/asked, is this something to really lament?
A world where everybody looks, speaks and acts like everybody, is a world of boredom.
Brooklyn/NYC dialect should be preserved as a cultural heritage. It’s just stupid and sad to hear a Brooklyn Jew or a Jersey Italian speaking like someone from small-town Iowa.
My two agorot.