Sen. Pat Leahy (D-Vt.) just helped seal the deal on a Democratic filibuster of Supreme Court nominee Neil Gorsuch. And in announcing he would be one of 41 senators to uphold it, Leahy admitted exactly what he was doing: Helping kill off whatever was left of the U.S. Senate he had known for much of his four decades in it.

It was a pretty striking eulogy.

“I respect this institution as much as anyone; I never expected to be here long enough to become the dean of the Senate, but I have,” said Leahy, who was elected in 1974. “And for those 42 years, I've devoted myself to the good the Senate can accomplish.”

Then came the but.

“But I cannot vote solely to protect an institution,” he said, adding that “I fear that the Senate I would be defending no longer exists.”

Leahy is 100 percent correct. All the hand-wringing about whether Democrats would actually filibuster Gorsuch — a move likely to cause Republicans to “go nuclear” and simply change the rules to get rid of filibusters for Supreme Court nominees — kind of misses the point. Our politics have changed, and the Senate has changed along with them. The writing is already on the wall for a dismantling of the filibuster for Supreme Court nominees (and perhaps more).

Through a combination of our own polarization, Democrats' 2013 move to get rid of the filibuster for non-Supreme Court nominees, and Republicans' move to not even consider Merrick Garland's Supreme Court nomination last year, we have effectively written the death warrant for the Supreme Court filibuster. Democrats are merely in the process of figuring out whether they want to sign it this week or a little later. Then, Republicans will gladly seal the envelope.

It's what I've labeled the “mutually assured destruction of the filibuster”:

Part of this is certainly Democrats' hard feelings about Garland. But perhaps it's also that they know Republicans are very likely to nuke the filibuster regardless, whenever it suits them.
Trump, after all, has already signaled that he's very much in favor of the nuclear option to confirm Gorsuch. And given his authoritarian streak, there's basically no reason to think he won't say the same about any other filibustered legislation over the next four years.
Republicans also know they probably wouldn't be punished for it. Americans collectively shrugged when Democrats rolled back the filibuster rules in 2013 and when the GOP wouldn't give Garland a hearing with a full 10 months left in Obama's tenure. Democrats hoped and prayed that people would care and that they could attack vulnerable Senate Republicans for going along with the gambit. But people didn't care — at least not the ones who could help Democrats win elections — and the strategy was quickly abandoned.
The reason people didn't care is because there is little nostalgia for the norms of politics these days. Whatever norms Trump didn't squash in his 2016 campaign were already on the way out because of our partisanship.

Also acknowledging the unfortunate role Democrats were playing in further killing off the filibuster was Sen. Christopher A. Coons (D-Del.), who just a short time ago became the crucial 41st vote to uphold the filibuster and force Republicans to go nuclear.

In announcing that decision, Coons said, “The reality we are in requires us over the next several days to consider what both Democrats and Republicans are doing to this body, and to consider what both Republicans and Democrats have done to erode the trust that has long lasted between us ...”

Coons added: “The traditions and principles that have defined the Senate are crumbling, and we are poised to hasten that destruction this week.”

Leahy and Coons were two of the final holdouts on supporting the filibuster. And in announcing their decisions, they made it clear they didn't like what the Senate had become — and, in a way, what they were forced to become along with it.