Grew up in Chicago, live in Washington D.C., have plenty of experience on the coasts and in flyover country.
Panda Express is the largest national “fast food Chinese” place here. It’s not everywhere, but it’s got the greatest market penetration (Some free-standing, some in malls). It’s not bad. Best thing about it is it’s standardized-- unlike the crap shoot of regular Chinese take-out, you always know what you’re going to get, which is largely the point of fast food.
Coming in second (I think) is, Manchu Wok, which is only in shopping malls (http://en.wikipedia.org/wiki/Manchu_Wok).
So, I’d say the market share is growing, but I doubt it’ll ever be terribly huge in the United States for one big reason: **you can’t eat Chinese food while driving a car. **
Remember-- Chinese food is very popular here in the U.S., but fast food in America caters to the car culture. Selling anything that requires a utensil, you’re automatically limiting your market to people who eat there (like in shopping malls) or people who buy it and take it home (which is enough of a hassle for most people to obviate whatever benefit “fast food” brings you-- at that point, most people just order in from their local takeout place, I figure).
Indian food is getting more popular here in the U.S. It’ll probably be a while before anyone figures out how to make it into fast food, however. When they do, it’ll probably have the same challenges fast-food Chinese will have, unless they market Naan-based wraps (which I’m all for, BTW-- just call it an Indian gordita!).
Personally, if I had to venture a guess, I’d say the “exotic foreign food pecking order” in the U.S. right now is:
- Japanese. Sushi is really close to mainstream now in much of America, you can buy it in most upscale grocery stores, and find independent sushi stands in many malls. Hell, there’s even a popular sushi restaurant in Wisconsin Dells I routinely visit, and for anyone who knows the Dells, that’s about as flyover as one can get
- Thai (almost as common as Chinese in many cities)
- Indian a distant third.
A lot depends upon geography. Go to Texas, you’ll find more Mexican food, obviously. Here in Washington, however, we have a lot of South American food that you can’t find elsewhere because we have more South American immigrants here. I swear that if I ever figure out how to franchise the recipe for Peruvian rotisserie chicken in Chicago, I’ll be a gazillionaire. (Just as if I can ever import a combination Chicago hot dog/Italian beef/White Castle here in D.C.).