It's not New Orleans and Baton Rouge that are the issue; it's the area in between. Southeast Louisiana ought to be doing a lot of its growth along the river anyway. Eventually, you can put an airport in between, and in about 20 years, even if the rail runs at a (tolerable) loss, you've put in the backbone of a 70-mile metroplex between Baton Rouge and New Orleans as BR grows southward and New Orleans grows up river.