Whereas allowing Gorsuch to succeed Scalia confronts Democrats with an even conservative-for-conservative swap, the next death or retirement from the court may well prove far more threatening. Liberal Justice Ginsburg is an 84-year-old two-time cancer survivor. The next oldest justice is 80-year-old swing-vote Justice Kennedy — a man who has contributed crucially to landmark (but still-contested) decisions on abortion (Casey) and same-sex marriage (Obergefell).

This means it’s likely that the next Supreme Court vacancy will be just as high stakes for Democrats as the current one is for Republicans. That is when Democrats will need the filibuster.

But wait — won’t Republicans simply vote to eliminate the filibuster whenever Democrats attempt to use it against a Supreme Court nominee, whether it’s now or during a future confirmation battle? Maybe. We can’t be sure. But I suspect there’s a greater likelihood of McConnell’s parliamentary gambit prevailing when it’s “their” seat at stake, which is right now. All it would take is two Republican senators to refrain from supporting the nuclear option for it to fail — and that’s more likely to happen at a moment when partisan imperatives are somewhat less heightened on the right, allowing considerations of institutional tradition and collegiality to prevail.