The new American cuisine no longer represents the food made in the kitchen a couple of generations ago. It even has its own restaurant category. American (new) as opposed to American (traditional).
Pizza and burritos are on the verge of becoming mainstream, if they haven't already. An entirely new cuisine can get incorporated into another - rijsttafel originated in Indonesia, but it's now a form of traditional dinner enjoyed in Holland.
Time seems to be the key to feeling at ease with something new, initially met with cautious welcome or possibly hostility.
What are the foods long ago introduced as novelty which have comfortably taken their place in the mainstream American cooking?