As I explained, I think that concerns that the absence of the Supreme Court filibuster would lead presidents to make extreme Supreme Court picks are misplaced and belied by history. But let’s assume for the sake of argument that those concerns aren’t baseless. It still would make no sense for any Republican senator to strike a deal with Democrats in which he or she would commit not to abolish the filibuster for the next nominee.
Briefly put: The power that a few Republican senators have now to strike a (foolish) deal with Senate Democrats to avoid a filibuster fight on the Gorsuch nomination is the very same power that they would have to join with Senate Democrats to defeat a hypothetical “extreme” next nominee. So why confer on Senator Schumer and other Democrats a preemptive veto on any next nominee, even if that nominee turns out to be someone you strongly support? The intelligent move is instead to hold on to the free option and exercise it only if and when you face a nominee you can’t support—that is, by voting against that nominee.