Literally and figuratively the Trump administration is polluting America. For a literal example, the EPA is letting major polluters get away with spewing poison into the ground, water, and air. Figuratively, Trump is polluting democracy.
If we stay out of a war where lives are lost most of the damage can be reversed and in time, undone, if and when the Democrats control Washingon. We have to count lives ruined by Trump's cruel draconian obsession with immigration too. That can't be undone except by inviting dreamers back and facilitating their return.
The only Trumpian legacy that will last a generation or more is in the judiciary.
Notwithstanding the rightward swing in the third branch of government, a Democratic president can reverse Trump’s executive decisions. If the Democrats control both houses of Congress each and every piece of legislation that doesn't require a supermajority can be reversed.
If Trump survives to run again, even if 80% of the Republicans vote for him, that isn't enough to win the general election unless there is major election fraud. If Pence runs, he is a poor candidate if he's matched against a Democrat that can pull in Republican voters who have soured on four years of Republican control. He would most likely lose to a relatable candidate who isn't threatening to white non-college educated men.
When I feel despair over the future of America, I have to remind myself that the Constitution which allows people to own assault weapons (according to the NRA), and The National Enquirer to publish pizzagate stories about Hillary also enshrines a system of checks and balances.