There's also too much competition in the criminal world nowadays for LCN to have any type of monopoly or stranglehold on crime like they did back in the earlier part of the 20th century.
The LCN's influence and reach has receded while other criminal organizations and gangs have emerged and grown into legitimate threats. And it's not just other typical organized crime entities like the Russian or Asian mobs but also the proliferations of various street gangs that have infested and overtaken many former Mafia strongholds.
Way too much competition and way too many rivals. The changing U.S demographics have helped speed the decline of the Mafia while fueling the rise of other ethnic criminal gangs and organizations.
I doubt the LCN is even the strongest in the Northeast anymore (maybe the most well known).

During Al Capone's day in Chicago, he basically ran the entire criminal underworld in the Windy City. Today? What does the outfit control -- a few streets/blocks?