I guess any port is vulnerable.
A good lesson.
One of the things that let the Port of Houston really prosper was the destruction of port facilities at Galveston after their Great Storm.
Ports being at the water are vunerable. What NO had going for it was a broad expanse of navigable river, rail lines, barge traffic, and being the last major place on the Mississippi draainage.
Probably, after they get the ship channels cleared, it will go back to being an important port (you don't need a lot of city. You need warehouses, road and rail connections, and a place for the barge and ship traffic to tie up to) because of the geography of how it's easier to get goods down river and out. The lands near the river are above sea level. A lot of stuff on the other side of the river faired quite well.
But it will lose business. And some of that business will never come back because there are alternatives.