Trillions of dollars in assets interact with Linux in one way or another. There are other people with intimate knowledge of the kernel. One of his deputies would replace him and things would smoothly continue on.

Nothing. Steve Jobs died and Apple continued. Billy G. left Microsoft and they continued.

Someone always continues.

Maybe a few days of slow down, but possibly not even that. Greg KH will take over as he already does when Linus is on vacation, maybe a bit slowdown for a few days until it is officially decided (although I don’t know who it would be up to decide such a thing, actually).