Attempting to change nature usually invokes the "Law of Unintended Consequences". Although it may seem fine at the time, the consequences of such a diversion would produce consequences not thought of that may or may not (as is usually the case) be good.
I think we just had the unintended consequence. I may be wrong but I think the Mississippi would be using the Atchafalaya today if not for the dams and canals the Corps of Engineers control to kepp it on its present course.
Actually, if we had let "nature take its course" the Mighty Mississippi would have made a change in course. It is man's intervention that has kept it on its present course.
"the consequences of such a diversion would produce consequences not thought of that may or may not (as is usually the case) be good."
Exactly. It is easier for us to adapt to the river. They can start by not building below the level of the river.. just off the river.
The Mississippi is NOT going to change for them. It hasn't for hundreds of thousands of years. Galveston adapted to their situation.. and it worked. Same here. The citizens just need to get the will and get it done!