ring the knell of

ring the knell of (something)

old-fashioned To foreshadow, signal, announce, or proclaim the end or ruin of something. Refers to the sound of a bell ringing (the knell) from a church to indicate that someone has died. An uproarious applause strained the very timbers of the chamber, and rang the knell of slavery in this country forever. The geometric expansion of the Internet and digital media has rung the knell of countless print-based businesses around the world.
See also: knell, of, ring

ring the knell of

announce or herald the end of.
The image here is of the tolling of a bell to announce a death or funeral.
See also: knell, of, ring