The new Democratic majority in the House is teeing up some impressive goals for the next two years and some critical issues for the 2020 election: climate change, gun safety, healthcare reform, getting rid of dark money, a return to voting rights protections. Some of these issues are existential, namely health care and climate change, and a new Democratic trifecta of the White House, Senate, and House will need to take immediate action on them. Assume we're able to achieve that, and a new problem crops up: the filibuster.
The Senate map for 2020 is favorable to Democrats, but not 60-vote-majority favorable. When some of the existing Democrats are Joe Manchin, Kyrsten Synema, and Jon Tester, even 60 votes isn't likely to cut it for a Democratic majority when it comes to the really big-ticket, important issues. Assume an absolute blue tsunami in 2020, and the Democratic majority will still likely be in the 52-53 seat range.
In which case, Mitch McConnell still has an effective veto (unless he's a victim of the tsunami) and still has the filibuster. That's a given. "The Senate is always the dream-catcher for stopping the most partisan and ideologically far-reaching proposals out of the campaign," said Josh Holmes, a confidant and former top aide to McConnell. "What it does is protect the American people from wave elections one way or another" and "forces all legislation toward the middle." (Never mind that that's not what McConnell has used it for at all: He's used it for the Republican Party's increasingly extremist right-wing agenda.)
What it means is that eliminating the filibuster has to be part of this cycle's discussion, in the presidential and Senate races. Thus far, the declared presidential candidates who've weighed in on it are Sen. Elizabeth Warren ("all options are on the table"); Kamala Harris (the issue is a "difficult one and I actually am conflicted"); Sen. Bernie Sanders ("not crazy about getting rid of the filibuster"); Gov. Jay Inslee ("the time for the filibuster has come and gone"); Sen. Cory Booker ("We should not be doing anything to mess with the strength of the filibuster"); and Sen. Kirsten Gillibrand ("I just want to think long and hard about it"). Sen. Amy Klobuchar has also declared and signed on to a letter in 2017 to Senate leadership saying that the legislative filibuster must be preserved. Sen. Sherrod Brown, who is still a potential presidential candidate, also signed on to that letter.
The field is heavily loaded with senators, most of whom are playing it safe on the filibuster now presumably in order not to make too many waves in their current jobs. They also know from direct experience that if one of them happens to get that brass ring, their agenda is going to be stopped from day 1 if the filibuster stays in place.
They all have enough direct experience with Mitch McConnell to know that he'll make using veto power over their ambitions his top priority.