Yes, then the USA's economy would fail so bad everyone inside would die. For example, not too long ago there was an oil spill in the Mississippi River. For everyone's safty they shut it down. Due to this shutdown, America lost 2.5 million dollars a day. Without New Orleans, they might as well shut down the Mississippi River.
The money was lost because of the barges and other vessels couldn't travel up and down the river, not because there weren't a bunch of poor people living in a bowl right by the ocean.
You really think we should rebuilt New Orleans? Why? it was a city of crime. Since Katrina, many "victims" came here to Houston. Crime rates here increased 50% since that event. In another experiment before Katrina, college students, as an experiment, got the local police department in New Orleans to fire off 500 blank rounds of ammunition in neighborhoods all across the area. Not a single call was made to report the shots. No one cared.
FEMA came into to help people in need, but like the dipstuffs they are they looked a gift horse in the mouth and complained about it being too slow to arrive.
If a man jumps in front of a speeding car and dies, do we feel sorry for him? Maybe its sad because a man lost his life, but we must remember it was his own fault. Similarly, the residents of New Orleans made a similar choice and they paid the price for it.