Of all the horrors Donald Trump has (and has yet to) inflict upon the republic, a huge tax cut for the rich was the most inevitable. But it is also the most easily reversible. Lifetime court appointments, carbon pollution, the degrading of democratic norms — all of these will prove difficult or impossible to undo, and leave costs deep into the future. The Trump tax cuts will not.
Indeed, the passage of the Trump tax cuts will help lay the groundwork for their undoing by increasing the chances Democrats regain control of Congress. The moment Trump won his election last November, he immediately forfeited his most potent advantages: He no longer had the deeply unpopular Hillary Clinton as his opponent, and he lost the advantage of Democratic complacency (which tends to build up over time when their party holds the White House.) An anti-Republican wave of some size was always inevitable. But Trump compounded the problem by surrendering another potent advantage: his brand as an economic populist loathed by the financial elite and planning to raise taxes on rich people like himself.