The two most reliably conservative justices on the U.S. Supreme Court are also the two oldest: Clarence Thomas (75) and Samuel Alito (73). By the end of the next presidential term, their ages will be 80 and 78, respectively.
If the two of them were replaced by liberal justices, the current 6–3 conservative majority on the Court would become a 4–5 minority. There is little doubt that this would mean, for starters, the reversal of the Court’s recent decisions on abortion, racial preferences in university admissions, and the Second Amendment. You can add any number of other reversals of good decisions, extensions of bad decisions, and brand-new horrible decisions.
So this is another reason why it would be good if the Republicans nominated someone who might actually win the 2024 presidential election.