We are constantly told about the need for "diversity". This term is defined in a specific manner by the persons who tell us how important it is, and the arguments in favor of that specific definition are phrased in such a way as to make opposition seem bigoted.
The larger question is what "diversity" really means, both to individuals and to society. Ethnic food and folklore are both "diverse". Beliefs and attitudes, likewise. Races and creeds, also. All of these can coexist in a free society. But can widely divergent cultures coexist in a free society?
The answer, actually, is "No".
This seems counter-intuitive at first. However, the foundation of any successful society is a shared set of laws and values. Ethnicity, religion, and politics may vary widely in a society, but respect for law and respect for one's fellows must be paramount. This is, I submit, the true definition of "culture".
This sort of respect is precisely what we do not see in today. The Left has no respect for the values of the Right. Radical Moslems show no willingness to live in peace with Christians -- or with anyone else. Practitioners of divergent social lifestyles don't ask for acceptance, they demand it, no matter how repugnant others may find their beliefs. Meanwhile, their opposites -- conservatives, Christians, traditionalists, etc. -- are forced to respond in order to protect themselves.
In such a climate, what we have is not a functional society, but merely a Balkanized conglomeration of competing interests and groups. A conglomeration that will eventually fail. When that failure occurs, it's not a great stretch to imagine that the society or societies that relace it will not hold to the current standard of diversity, but instead be defined by a primary culture, that culture being established by the victors.