True, I think there are some who move to other parts of the country but keep allegiance, or retirees:
—People who went to college in Boston area become Red Sox fans; might move to California and go to Angels games when Red Sox play in Anaheim
—Retirees...New Englanders might settle down in Florida
and stay Red Sox fans, attending TB vs Red Sox games,
or spring training (Jet Blue Park, Ft Myers)
Some? Go to a yankees game in tampa or a buffalo game at the hockey rink.