Years ago, Tom Harkin came up with a reasonable solution for killing the filibuster — a gradual phase out. Ironically, Lieberman was on board with the plan.
The plan he announced with Lieberman 14 years ago would have slowly scaled down the cloture threshold for legislation that had been filibustered. The first vote would require 60. If it failed to reach 60, debate would continue until a new vote, which would require 57, and so on until a simple majority could determine whether the measure lived or died.