US Authoritarianism

If we're lucky, outside intervention in the ensuing civil war. If we're unlucky, outside intervention but they're fascists.

I suspect we're in the boring dystopia timeline though, where things just gradually get worse until climate refugees provide an excuse to close our borders until enough people die to change the dominant political demographic. The rich and powerful flee to somewhere not overburdened with drought and famine and never see consequences for their actions.