I personally have to say that it varies between families and their choices regarding their way of life. On one hand, you could have a family that comes from the same foreign country where the spouses marry and have kids but move to the US for economic reasons (where the language and culture is different). Ultimately, this would have the children to grow up in a society completely different of their parents, instilling the notion of assimilation (unless the children uphold/maintain any connections to their parents way of life).
On the flipside, you could have a family that still immigrates to the US and instead of having its children assimilate “100%,” they could move to a town/city that has a considerable amount of people with the same heritage (i.e. Little Italy, Chinatown). Furthermore, depending on the conservativeness of the parents, the children could very well end up marrying within their own culture (on top of upholding any values of their old homeland such as going to church, celebrating certain holidays, etc.) In this scenario, you would have pluralism where the US would still keep that melting pot of cultures within the country.