The Fallout 4 Survival Mode isn't even officially out yet, but a whole host of changes are on the way.
These tweaks are coming out of the beta release which was put out on PC last week, and Bethesda is already making changes in reponse to how it has been received. From the list of updates below it seems like balancing is a major part of the beta test, as elements like how much food you have to eat to stay healthy have been changed to a lower amount. It's interesting to note that while some elements have become more forgiving, others have also been made harsher, suggesting that players want a challenge but one that feels like it responds to some rules of reality.
See the list of changes below. Survival Mode will arrive on consoles when the PC beta testing is complete.
New Survival Features
Thirst, hunger, sleep and disease icons will change color based on status
Less food and drink are required to maintain proper sustenance
Carry capacity lowered
Sleep cycle has been lowered from 24 hours to 14 hour days
Reduced chances of getting a disease
Fusion cores weigh more
Nuka Cola Quantums no longer cancel out caffeine effect from Nuka Cola and Nuka Cola Cherry
Fixed occasional issue with becoming parched or peckish when thirst or hunger are actually satisfied
Fixed issue where Adrenaline effect would incorrectly persist after changing difficulty level
When companion is down, a quest target will appear on them