One scenario for life after 2018
If Democrats take control of Congress, Trump's main option for legislation (to the best of my understanding) is executive orders, assuming Congress has the power to vote down anything he sends their way.
Congress can revoke, modify, or supersede an executive order if the president was acting under authority granted by Congress: But if Congress makes changes that the president disagrees with, it can expect to face a presidential veto, which it could only override with a two-thirds vote in both the House and the Senate. One 2006 study (pdf) cited by the Congressional Research Service found that only about 4% of executive orders have been modified by Congress. Usually when they do act, its to provide funding to an executive order, or to build an executive order into a statutory framework, says William Howell, a professor of American politics at the University of Chicago, who has written extensively about executive power. They fortify an executive order.
https://qz.com/898683/can-an-executive-order-be-revoked/
So, in other words, 2 years of back-and-forth between Trump and Congress with Trump chasing his tail.
Sound logic? Faulty logic? Looking for your take on this.