Spengler would have hated this because he was afraid the non-white races would adopt our technology and use it’s against us. However since I’m not a racist, with a zero sum fear of the foreign, I think that’s fine. They’re part of our civilisation, or at least are rapidly becoming part of it just like Japan, Korea, Taiwan etc.
The one outlier is China, which against the odds has managed to ditch Communism, adopted radically laissez faire Capitalism, yet retain one party authoritarianism. They seriously worry me, but not for anything to do with Spengler and the inherent instability of civilisations.