Back in the summer of 2013, when Senate Majority Leader Harry Reid (D-NV) was threatening to nuke the filibuster for nominations, Senate Minority Leader Mitch McConnell (R-KY) made a threat of his own.
"There not a doubt in my mind that if the majority breaks the rules of the Senate to change the rules of the Senate with regard to nominations, the next majority will do it for everything," McConnell said on the Senate floor on June 18, 2013. "I wouldn't be able to argue, a year and a half from now if I were the majority leader, to my colleagues that we shouldn't enact our legislative agenda with a simple 51 votes, having seen what the previous majority just did. I mean there would be no rational basis for that."
Reid went for the "nuclear option" later that year, enlisting 51 other Democrats to eliminate the 60-vote threshold for all executive branch and judicial nominations except the Supreme Court.
Now McConnell is poised to become majority leader in January.