Let's see, NE becomes the Boston Patriots. The Jets (and Giants) both get to keep New York, though; state lines aren't what's important here, New York's still the nearest major city, Newark be damned.
New York is the birthplace of a lot of stuff; let's go with No Wave, about which there's a new documentary out now. Miami is the birthplace of Miami Bass, which I've never much cared for, but if you're interested there's a good overview here. Boston is the home of a bunch of drunken narrowbacks celebrating their heritage by ripping off the Pogues all night long in pretty much every other bar.
Buffalo was the home of the late, lamented Astronaut-Lost, with whom my band once played a gig at the Mohawk, but who now have almost no remaining web presence. If you can ever find a song by them called "Some Day You'll Realise My Dreams of Yours" or something like that, listen and believe. There's an excerpt posted in the last link; scroll down and listen to "mp3#1" off their EP. One of the great lost classics of this era. I have no idea what those guys are doing these days. Tristan, if you read this, I hope you're well.