Extremely unlikely doesn't mean impossible.
The Supreme Court's a pretty big deal, and with President Trump's second nominee about to enter the confirmation process, some are a little freaked out.
Adding members to the Supreme Court is one of the longest-lasting legacies a president can have. For decades to come, the Justices of the Supreme Court of the U.S. (SCOTUS) will shape the country and its laws in powerful ways.
That's enough to make anyone feel a little anxious, regardless of their political views. It's especially worrisome for anyone who has anything less than complete trust in Trump's judgment or worries about any of the specific issues (abortion rights, LGBTQ rights, civil rights generally) likely to come before the court in the near future.