Every cell in your body needs thyroid hormone to function. If you have no thyroid gland, your body progressively shuts down. Myxedema coma can cause death. It wouldn't be pretty, and I suspect you'd wish you were dead long before you actually were.
How do you feel? Do you have hypo symptoms?
You will have severe fatigue, depression, anxiety, dry itchy skin,mental confusion only to mention a few, then you will die, you cannot survive without thyroid hormone FTB4