The demise of the Colombos is not anything we're gonna witness in our lifetime.

Despite any of those places not being as prevalently "Italian" as they once were, there's about 2,5 million Italian Americans living in metro NYC and New Jersey, half a million in metro Chicago, 150.000 in metro Philly, 300.000 in metro Detroit...15% of New England is of Italian descent...etc... And it's not a secret the Mob has been rebuilding. The glory days are over, but they're steady and stable and have been a force in American organized crime for about 100 years now. What other group can make a claim on this?
Plain and simple, the American Mafia is a brand. And even though they're not as all powerful, as flashy or as feared as they once were, there's no shortage of people who'd want to be part of a brand.

It's gonna take a long long time before the recruitment pool for the Mafia on the East Coast and even the Midwest has been completely diminished.