And for southern exports and imports, and for access to the west via the Mississippi, much less so. And since the tables Pea gives us in the #779 link show that 1,918 ships visited New Orleans in the 12 months prior to August 31, 1860 ( a figure that doesn't include steamboats, btw), it's pretty clear that New Orleans was a thriving, major port.
But there's something unreal about the whole debate. Northerners who read DeBow's or heard Hammond's speech about "King Cotton," knew very well that the South of the 1850s and 1860s wasn't about to turn itself into an industrial powerhouse. The betting was on cotton, and industry and commerce were to be servants of agriculture, not rivals or masters.
Also, it's not just a question of what Charleston or New Orleans was preparing to do in the 1850s. Dredging and canal and railroad building where going on all across the country, and there's little reason to believe that one city's joining in would bring it all the goodies. There would always be competition. And planned "great leaps forward" often come to nothing.
Indeed, 21st century New Orleans may have some real problems with economic development and survival, even without the threat of yellow fever.