Not so long ago it was Wayne Static and 15 years ago it was Dave Williams.
In additional to the personal tragedy, Chester is the biggest casualty the music industry ever took, and while Mick Shinoda is a great talent himself, and may find a way to let the show go on, listening to Linkin Park in the future will contain a saddening effect, regardless of how it will sound, assuming they will not disband and assuming they will maintain a semblance to their old selves.