Liberals complain about Justice Barrett being appointed to replace RBG, but they never want to blame RBG for staying too long. She made her choice, and decided to try to outrun Mother Nature. It didn't work.
See, conservatives understand the value of planning and preparation far better than liberals. Not sure why that is, exactly, it just seems to be baked in for some reason.
But even though liberals probably won't ever get it through their heads, and most liberal justices will likely continue to repeat RBG's mistakes, I think some Democrats somewhere along the way will eventually realize that when they hold both Congress and the White House, they have sufficient power to effect change without resorting to anything as radical as court packing. It's very simple. All they need to do is create a temporary expansion of one Justice.
Next time Dems controls both Houses and the Presidency, they should pass a bill that expands the court by ONE justice, and further specifies that upon the next naturally occurring vacancy in the court, the new vacancy will become null with the court returning to its previous size. They can then have their President add one more justice.