How has Spain been able to hold on to Luisiana until the era of Mexican independence (whenever it occurs in this alt TL), through the Napoleonic era and through the initial stages of american westward expansion? These hurdles need to be jumped first.
The Spanish managed quite well
Luisiana as far as I know, there was considerable Canarian ("
Isleño") migration to Lousiana Proper. I fear, however, that a "Texas-like" situation is almost inevitable regarding Upper Louisiana. New Madrid, Missouri was founded by the Spanish to accommodate Anglo settlers... In the end, I think that the fate of Lousiana is a matter of how stable/strong are Mexico, USA, Britan and, possibly, France.