What if the Trump regime runs off the track? Consider the possibilities.
The first scenario is that the collective authorities: FBI, CIA, and Treasury determine that Donald Trump and his emissaries engaged the Russian government via contacts for the purpose of advocating that Trump would be a more favorable President than alternatives including Hillary Clinton. Interpreted that could be that Trump initiated cooperation or collusion in getting him elected.
The Russians responded favorably by hacking and leaking information about Democrats and Clinton with Trump cheering them on from the campaign trail. The Russians launched a fake news propaganda campaign.
That fact alone, if proven in a court of law, would be sufficient to nullify Election 2016 results as the process was corrupted by foreign influence in cooperation with the candidate, Donald Trump.
Trump would be impeached and possibly tried for higher crimes, including treason.
Another parallel scenario is that Donald Trump has violated the Emolument Clause of the US Constitution. IRS records and other intelligence may support the claim that the President has a multitude of conflicts of interest that may or may not involve the Russians.
If the conflicts include Russians, following Trump's denial of having any business with them, then more high crimes are involved.
It is eventually going to come to a trial to impeach Donald Trump, removing him from office.
The second in command is Mike Pence. If Pence is proven to have co-conspired with Trump or otherwise covered for him, he could be declared an illegitimate heir to the presidency, even when that is the Constitutional protocol.
What comes next is a series of investigations and vetting of the Speaker of the House and Senate Pro Tem. If they too covered for Trump's illegalities or obstructed justice, then they would be illegitimate.
Eventually, the question will be "Who is in charge here, and what is the way forward?" That will be a question to be answered by the Supreme Court.
At some point, those in Congress from both parties who have not obstructed justice and who are legitimate incumbents will employ the rule of law under the advice of the court to call for a new election. In the meantime, a temporary government will be installed until the new election is complete.
That analysis is the point of view of a citizen journalist trying to make sense of the possible situation.
US Supreme Court