If Trump wins then that's it, for the world, really. The US will convert to a theocratic dictatorship, ruled by religious doomsday nuts with nukes. Trump is, as usual, the puppet of Putin, so do expect the US not only to withdraw from Europe, I fully expect him to actively help Russia to conquer more parts of Europe than the USSR ever had.
Am I overthinking and overstating things? Most of it is based off Trump's words and actions, the Republican 2025 documents, and well... Maybe a lot of pure cynicism as well, as I've seen humanities behaviorfall of a cliff