Expect to die a lot then with not seeing your health bar. :goodjob:
There are other ways to tell your health. When you are at low health, your heartrate speeds up and you can hear your heart beating fast. You also breathe loudly and canhear your rapid beating along with your heartbeat. You can also check your health by looking at your pip boy.
Or hunger or dehydration or exhaustion. Actually this sounds great! Imagine the paranoia!
Again, there will probably be pip boy measures of how thirsty, hungry, or tired you are, since your pip boy measures all vital signs. There will also likely be immersive cues not unlike the effects for low health cues. For example, your vision might get blurry or wavy, you might start stumbling when you walk, etc. Your Pip boy face will also likely reflect how you're feeling at the time.
Imagine the annoyance.Haven't saved for a while.Autosaved only.Then after exiting a building you die from dehydration.Reload.Quickly open inventory.No drinkable items./rage????Profit!!!
For you, it's an annoyance. For others, it's a challenge. Remember to save often, remember to eat and drunk regularly, and try to get some shuteye whenever you can. Besides, I'm pretty sure dying from any of the hardcoe survival features takes a while. There will be a good long period in between when the game's cues will tell you that you are dangerously thirsty/hungry/tired and when you keel off. And before then there will likely be lesser tiers of hunger/thirst/exhaustion that merely reduce your stats a bit, but still serve as a warning that you should take better care of yourself.
It wouldn't annoy me, I'd blame myself, not the game. If you are smart about how you play getting killed by dehydration should never be a problem.