Loosely speaking, probably not right now. A lot of countries avoid war because they are worried about the potential response from the United States. With an isolationist-focused US that isn't the dominant military power (in order for the US to not be the dominant power it'll have to undertake more isolationist tendencies like reducing military spending) there's nothing to fear from invading your neighbor.
But this is just an examination of practical reality. Ideally we wouldn't have a hegemon. Ideally maybe we wouldn't have countries either.
The wildly different allocation of resources and population (on a country border basis) suggests some country will always have the means to be hegemonic (especially if other contenders all decide not to be).
Which in practice means there will always be a hegemony.
If the US ceded its role tomorrow, China would step into it. If China ceded it the day after, Russia or the EU would step into it. (I'm skipping over India and Japan, as both seem to have cultural aversions to strongly projecting power overseas)
This is laughable. The US initiated way too many wars and other offensive / disruptive actions. If you call this stability then I have a bridge to sell. The only stability it provides is it's own. Well maybe some to the allies.
The US Navy ensures that global shipping routes stay open and safe, the US economy provides the globe with advanced technological research and products, and the US's natural resources allow for it to export tons of commodities including food and energy.
During pax americana, we've seen massive increases in quality of life around the world. Do you think the world is going to be more stable as the US retreats and other players fill the power vacuum and we have to deal with the rising threat of climate change?
I think the world will be more stable when there are few major players around with not a single one having complete control / dominance. This will insure competition and cooperation between our "masters" and will keep them on their toes.
I appreciate your desire for the world to be ruled by the US. I do not think the rest of the world will agree. And if you enforce it using military means you are no better then the rest. Are you American by any chance?
But this is just an examination of practical reality. Ideally we wouldn't have a hegemon. Ideally maybe we wouldn't have countries either.