Many are worried that pardons by Trump or the firing of the Special Prosecutor would trigger a constitutional crisis. This is understandable. The notion that a suspected criminal could pardon people who might implicate him or stop the investigation is clearly at war with the rule of law. The rule of law calls for an impartial investigation. It does not call for a suspected criminal to pardon people or stop investigations for illicit reasons. Even assuming that the Courts would uphold such actions and assuming that the spineless Republicans would continue to cater to the deplorables in their base by looking the other way, Robert Mueller has a backup plan that will mitigate the damage.
Perhaps you noticed that Paul Manafort was not charged with all the felonies implicated in the indictment. Tax evasion is one of the most conspicuous omissions. If the factual claims of the indictment are accurate, Manafort engaged in a massive scheme of tax fraud. Why is that charge not included along with others? A Professor of Law at Fordham, Jed Shugerman, explains that this is a brilliant move by Mueller, not an oversight. https://www.slate.com/articles/news_and_politics/jurisprudence/2017/11/robert_mueller_s_brilliant_strategy_for_outmaneuvering_trump_pardons.html
It is well known that Mueller and New York Attorney General Eric Schneiderman have been working together. New York law does not permit state prosecutors to bring charges already pursued by federal prosecutors. So if Mueller is pardoned by Trump, some crimes will be off the table. But Eric Schneiderman will have plenty of charges left to file against Manafort, and the President cannot pardon anyone for state crimes.
When complicated and sleazy financial transactions are implicated, multiple felonies can be charged. Mueller will have the option to use this strategy against Jared Kushner, Ivanka Trump and many others if the evidence warrants. At the arraignment of Manafort, the prosecutor stated that the indictment was a small part of a much larger investigation. It is not clear to me if New York state election law prohibits the kind of conduct suspected here. Leave aside the Trump Tower meeting and Trump’s false rendition of his son’s conduct, it is certainly fishy that so many people lied about contacts with the Russians (leaving us to believe they had something to hide) and it is also fishy that the Trump campaign and the Russians pressed similar themes. It would be unfortunate if state electoral laws do not reach such conduct.
It is clear, however, that state laws can reach financial crimes and Mueller has shown, he will leave room for that as protection if Trump takes more substantial steps to interfere with the investigation.