This is obviously a worst-case scenario, but I think that to prevent anything similar from happening Americans need to step up and pressure their news outlets to do better, and for social media platforms to be choked with regulation until they start preventing manipulative shit from spreading.
Manipulation is an unsolved human problem as old as humanity.
The core business model of social media is fundamentally based on manipulation.
Asking social media corporations to protect us from manipulation is salmon asking grizzly bears to protect them from getting eaten. It's contrary to their fundamental nature.
The questions is where to set the limits exactly and misinformation is indeed a grey area. Hence the discussion.
If you dare to debate and discern the wrong facts, you get a hit piece published on you like Slate Star Codex. Or you get fired like the NY Times reporter Donald McNeil Jr.
It seems some of the media play an enthusiastic part in stripping people of that ability, not in protecting it.
Many "smart" activists found that with a little faux rage (and in the end, believing their own BS too), all these pundit, policy advisor, and advocacy jobs are there for the taking...
A strongman.
An idea that I attribute to Imre Lakatos, is that if you strip people of the ability to debate and discern facts, you create a power vacuum that can only be filled by those who can act in the absence of debate and facts, notably thugs and tyrants.
I believe this is the actual motivation behind the "war on truth" and the flood of misinformation.