Surprisingly, it's bad news if we don't hear the rattle anymore; that means you have the approximate shelf life of pancake batter. Also, much like pancakes, you give off a sweet smell -- the result of acidosis, or the breakdown of internal sugars. Those hospital cats that can predict when patients die? They don't have Miriam Black psychic powers; they simply have a heightened sense of smell.
In your last days, you'll be so divorced from consciousness that you'd drown on a sip of water. That's why many people don't actually die of their illness -- they die of dehydration. But the drying-out process can start long before the loss of consciousness sets in. When your health starts to decline, you'll likely refuse food and water anyway. Relatives might suggest attaching an IV, but I (and hopefully the doctor) will discourage this. Your body may not do anything with the fluid, which means the water could accumulate and result in acute heart failure. With feeding tubes, the solution may do nothing but sit in your stomach, which puts you at risk for a severe infection that'd kill you faster than if you'd done nothing. Trust me, "rotting from the inside out via spoiled Ensure" is not the best way to go.
Having a feeding tube sucks enough without it killing you in the process.