> Global needs should have global support, such that the failure of one hegemony doesn’t fuck up everything for the rest of humanity

While this is true, I suspect that putting the UN in charge of all global matters will cause them to become such a hegemony.

Until we have multiple planets (or equivalents), I think a multi-polar world with multiple superpowers capable and motivated to work on such things is important.

Hopefully the superpowers will keep their fighting to "indirectly", like the USA and the USSR used to.