I don't know how you came up with that being multiculturalism but that is what White people have been saying for decades now. Interbreeding between races has become so standard, that it is barely even noticed anymore. I don't believe there is anything wrong with inter-race marriages.
You just have to look at Israel to see it. There are white, brown, black, and even Asian Jews living in Israel. But in the end, a Jew is a Jew, no matter the skin color.
Multiculturalism is about how a society accepts foreign cultures like in Britain, without question or demand of assimilation. For example, Bangladeshis bringing their backward culture to Britain and refusing to assimilate, fight against assimilation and demand their own society within the society.
If you want a non Jewish example, look at America. They, somehow, got it working for the most part.