You can't do social engineering on the scale of "destroying cultures" without risking the deep rooted, serious alienation of a set of people against you for doing that. I personally don't give a shit about preserving cultures, but I give a shit about defeating capitalism and advancing socialism. That requires solidarity, and it will require stages of development. You can't have a paternalistic mindset in this regard to subsets of people in some nation. Like, if you're talking about indigenous people or black people or something in America, if you treat them as a group to lord over and bargain with from on high they are going to resent you, especially when you sacrifice policies they largely identify with or prefer for something or other.
But ways of life are going to be destroyed and replaced in movement to a new political economy. We don't even know what that looks like, so there is no sense in which socialists or white socialists particularly can decide whether they want to "preserve cultures". Socialists prioritize the abolition of class society, and those conditions will create a new way of life that we haven't experienced and can't fully know ahead of time. But what we can do is fight class society and attempt to overthrow it in coalitions with other people who share our class interests, although they may also have other interests specific to them.