According to the 1840 Census, New Orleans was the 3rd largest city in the Union behind NYC and Baltimore. Your challenge is to keep New Orleans within the Top 5 largest cities up to the present day.
It would help if the city ever had honest, competent leadership. But even with the self-inflicted wounds, keeping the city in the top 5 would require an ASB, because you would need a geologic POD.
The metro area is too boxed in. Lake Pontchartrain to the north and wetlands in the other three directions. Contrast that to cities like Houston, Dallas, and Atlanta which can grow endlessly in every direction.