No Italians left in Brooklyn? Are you loco?
Visit Bensonhurst, Cobble Hill, Carrol Gardens etc.
There are still the local Pizzerias, bakeries, salumeria, ravioli stores, cheese stores etc. I shop there all the time. They are owned and operated by real Italians, their brothers and their cousins and nephews from the other side.
Mostly Chinese and Russian, with a smattering of Mexicans and elderly Italians. Only a handful of shops left on 18th Avenue.
Cobble Hill, Carrol Gardens etc.
Oh Puh-leeze. You are more likely to meet an attorney who grew up in California than you are an Italian American in said neighborhoods. Again, a handful of stores on Court and Smith, but mostly yuppie hell.
There are no "thriving" residentially Italian-American nabes in New York anymore, unless you count Staten Island. For food, NOTHING beats the Arthur Avenue/187th Street strip, however, in the Bronx.