I take the perspective that the United States is just tending towards the more typical behavior of presidential electoral systems. America will start acting more and more like Latin American presidential regimes, because the of the deadlock that presidential systems create. The checks and balances aren't protecting us. Instead, the checks and balances are what drive the public to elect "strongmen" who can "get things done" - often through illegal and unconstitutional measures. 

Trump for example is celebrated for "getting things done" - things that are often illegal and unconstitutional. That's the selling point. Therefore I'm not the only one who has suggested that presidential regimes are unstable. Yet as we look across the world, parliamentary systems also have their own problems with authoritarian takeovers. 

I write about what I think the solution is here.

In short, I think we can create a smarter democracy using a system called "sortition". Please take a read of the article I linked for more information. 

...

Even if sortition might be an interesting policy to you, it's not particularly clear if implementation is politically feasible. The inertia of the US political system is so vast it's hard for any money to budge it. Any financial investment will yield highly nonlinear results. Policy might not change for years, or decades, until suddenly one day policy changes. Yet just because the response to investment is extremely nonlinear doesn't therefore mean it's unwise to invest. (There's also the question if America is the wisest place to invest in. Pro-sortition movements also exist in Europe. Could pro-sortition movements be launched more easily in African and South America?)

In terms of what you can impact in terms of an idea such as sortition, your investment can be used to drive "public awareness" and "lobbying". Money can be used to persuade local governments to adopt pro-sortition policies. Or money could be spent raising public awareness of sortition - public awareness that might lead to movement growth. 

A post/submission I wrote to OP two years ago has some thoughts on this:

https://forum.effectivealtruism.org/posts/kmx3rKh2K4ANwMqpW/destabilization-of-the-united-states-the-top-x-factor-ea

It has some recommended readings and outlines potential interventions.

I'm still distilling what I would add to it in the present day.

The top thing on my mind is the proposed board to purge generals. (Note: presidents already have the authority to dismiss generals, however the implication of this proposal is that they want to purge so many generals that they need a systematic vehicle to do it.) As I wrote in my piece, our biggest bulwark against an authoritarian power grab is that the United States Military is very strong, professional, competent, and apolitical. Any changes away from that status quo should raise alarm bells.

The nominations to the military/national security apparatus are clearly about total loyalty over competence. These are the military and intelligence services that when captured in other countries by authoritarians have cemented regimes.

Interventions in the immediate term targeted at disrupting the consolidation of power (in the aforementioned moves) could be very high leverage.

For a longer-term intervention that focuses more on the upstream drivers of our political dysfunction which enables authoritarians, I still back the idea of doing local/state ballot initiatives to reform the political system. A gap I see in the space is that political system reform via initiatives is pursued piecemeal instead of comprehensively. Also, anti-establishment sentiments poll very high amongst Americans including the Left and Right, yet that bi-populist agreement is not being effectively tapped. Not only could mobilizing it help get initiatives over the line, but it would create depolarizing interactions between regular citizens.