There are several empires, American one is just the most powerful. The way the Chinese and the Russians treat their people does not give me hope that their empires would act any differently. Britain and France have shown they are not to be trusted either based on their past atrocities.
Would mutipolarity make things better or worse? I don't think that it matters, the fundamental nature of power and nation states make conflict and war inevitable. A multipolar world would likely make conflict more common. Can you name any wars of aggression that have honestly been done to improve the position of the country and its people and not just the elites? Vertical power structures are the problem, I would happily see the USA lose its position as hegemon but multipolarity won't change much.
The logical conclusion every country should be looking towards now should be acquiring nukes. Maybe this is the path to peace.