Fallout 4 received a fair bit of criticism for its Survival Mode that made the game harder, but didn't factor in all the dangers that made the mode such a hit with hardcore New Vegas fans. That will be amended in a future update.
Developer Bethesda Game Studios said on Twitter that it's "doing a complete overhaul of Fallout 4 Survival mode. Food, sleep, diseases, danger and more. Stay tuned."
In its current state, Survival mode's biggest changes are that you take much more damage, enemies have more health, and healing increases HP at a much slower rate. It's a fun challenge, but doesn't drastically influence how you play.
The developer also teased intel on an upcoming expansion that will be announced shortly. "We know youre ready to learn what's coming for Fallout 4 DLC. We're not far off, and we think you'll be excited."
In the meantime, Fallout 4 just received its 1.03 patch that improves draw distance and other visual enhancements on console, but doesn't improve performance. "Taken as a whole, Bethesda's update is an incremental step forward on console, but some pretty major stones still left unturned," wrote Digital Foundry's Tom Morgan in his patch analysis.