Part of the brilliance of Pixar, when they're not making stale sequels, is that they can take concepts that would never fly if you had to pitch them to an executive, and make them work. Like "a guy attaches balloons to his house, flies to South America, and meets his favorite movie star who tries to kill him with talking dogs." Or "a rat wants to cook."
Audiences who trust in filmmakers to take them on journeys, however, may not have quite the same boldness when it comes to food. And this is a Ratatouille tie-in pitch almost as bizarre as the movie's premise: a replica of a French restaurant as imagined by American animators, recreated in France, where the hook is that a rat is supposedly doing all the cooking. There'll also be a ride next door that simulates the feeling of being a small rat running around the kitchen.
The biggest issue it may face, however, is that, Anton Ego aside, most kids at Disneyland are not looking to eat ratatouille, the dish: eggplant and zucchini are rather consistently at the top of the gross veggies list for most kids I've met, and even some adults. Now, if they add on a Peter O'Toole-themed bar, THAT's something I'd like to see.