Let's not overstate the case. White decline will continue at a slow steady pace, but extinction is so far in the future as to be science fiction. The "kmowable future" will see a country that is less than half white, but still more white than any other one thing.
Balkanization of the USA, probably splitting into different countries, is inevitable at some point. It has already begun. Not just in the cultural arena but also in law, as some states recognize the US constitution/immigration laws etc. and others don't. So we are already a good ways down that road.
Let's not overstate the case. White decline will continue at a slow steady pace, but extinction is so far in the future as to be science fiction. The "kmowable future" will see a country that is less than half white, but still more white than any other one thing.