My guesses in order:
1. A quick service Gumbo and other Cajun food pickup window similar to Royal Street Veranda.
2. A New Orleans/Tiana themed Bibbidi Bobbidi Boutique. This would keep with the previous dress shop venue.
3. I think its really less likely but could possibly be a Disney kitchenware store, as others have mentioned. However what would guests do with the kitchenware's while walking around the Park? Its not likely its easy to lug around an 8 piece plate set all day.
The first two seem most likely, the third not so much. I mean seriously do we think they are going to put a Disneyfied Williams-Sonoma in NOS? They already have Disney Home in DTD, so just seems strange to me that it would be that, but its not out of the realm of possibilities I guess. So who knows....