You’re right. Gradually most white Americans will realize that the vast majority of the non-white peoples in our midst don’t care very much about those exceptional American ideals. It’s one thing to hold polite, egalitarian views when the minorities aren’t in charge and they’re just the happy couple next door. But when the whites are just one group competing among many, with the other groups often in charge, views will change whether the leftists want them to or not.
In the meantime, you can try to convince the blind that American exceptionalism arises from the white American people rather than arising from the noble ideals that only white Americans, as a whole, seem to hold.
Some of these whites will begin to listen when diversity starts to hurt, but probably not until then. People don’t change their minds until they start to get uncomfortable.