We had a flatter more multipolar world primarily run by the Church and imperialist absolute monarchies. There is no reason to assume a world not dominated by American imperialism but primarily made up of modern democracies and republics must revert to a 19th century status quo.
There's also no reason that whatever it does look like would be better than that, or even that the "modern democracies" we currently have would actually survive.
I disagree. The biggest destabilizing force in the world right now is the US. The loss of American superpower status will make the world and its democracies more stable practically by definition.
You might argue that absent American military hegemony, Russia and China become belligerent. But the US isn't really doing much about either, so that's a moot point. All the world really loses is America's interference in their affairs, which I think the world can do without.
