In 2010, Senate Majority Leader Harry Reid (D-NV) managed to get Senate Rules modified so that future Senate Rule changes would only require a simple 51-vote majority.
They did this as part of the process to pass the Affordable Care Act.
Back then, I said that this would come back and bite them in the ass, because, like ANY change you enact to get your way, there's always the chance that "some day, people you don't like are going to be in power, and you've just set a precedent they will use against you."
I hate to say "I told you so," but, well....
I told you so.