Of course, there is another real possibility of court-packing that we need to consider. What if the Court starts striking down Trump's executive orders? Ginsberg, Breyer, Kagan and Sotomayor probably won't be predisposed towards Trump, and predicting Kennedy can be tricky. Even predicting Roberts isn't always easy, lest we forget NFIB v. Sebelius, when Roberts saved Obamacare.
FDR responded to the Supreme Court by threatening court-packing when they started striking down parts of the New Deal, but FDR backed down from the plan.
Do you really think Trump would? Do you think congressional Republicans would restrain him?
Don't rule anything out.