Strap in, it's just gettting started.

Most dwarves have the option; unrepentant criminals don't get that option.  Some dwarves choose to stay in the Forges even when they have bodies; that extends their lives to the point of practical immortality.  Venturing outside the Forge without a body is technically possible, but forbidden with few exceptions after the incident where Mim haunted Finrod's bathroom for an entire winter.