I agree with Noah Smith here.
Although it’s not possible to know for certain what the consequences of a second Trump presidency would be, it’s very possible that it would result in the U.S. essentially surrendering its European allies to Russia and its Asian allies to China — thus dramatically weakening America’s own ability to resist those enemies in the future.
This is an extremely likely outcome of a Trump victory. And that, therefore, will make WWIII far more likely as well. Either that, or the below — followed by WWIII.
If the U.S. abandons resistance to China and Russia, it will go very badly for America’s allies. Europe will probably fracture again, with some states (probably including Germany) falling all over themselves to appease the Russians. Russia will then become a sort of de facto hegemon in Europe. In Asia, China would probably conquer Taiwan, cutting off U.S. semiconductor supplies and establishing Chinese hegemony in East Asia. Japan and South Korea would then be forced to choose between either becoming nuclear powers or becoming de facto satrapies of the new Chinese empire. Essentially, America’s major allies would fall to America’s enemies.
It is indeed, as Noah observes, a very dangerous time.