To be honest, if my only other option was to be buried, I would love to let my brain be connected to some machine that try to keep it as alive-like as possible. Just please don't remove my brain before I'm 1000% certainly dead.
There's some fraction of people who would prefer to be kept alive as a brain in a jar, depending on the alternatives, but getting to that point is going to require a bunch of people to volunteer to undergo excruciating torture as we learn how to keep the brain alive, how to keep them comfortable, how to keep them conscious, sane and let them interact with the world.