In the live stream Dan said for sure that the stealth system (which won’t be an actual system on its’ own) will work on situation based behaviour. So crouching will in general give you a reduced noise and sight bonus when you were never detected and/or being in dark areas, while it will draw attention on you, when you do it in crowded places.
I think there was no other information about any stealthing in the existing videos/statements.
edit: I think it was also said that your clothing will be crucial for sneaking. Dark light cloths will cover you better in the dark, while shiny armors will be loud and easily visible.
If the mechanics are proper for having well working stealth situations we would need to know:
- can we drag/move dead bodies (very essential for stealth imo)?
- when a guard finds a dead body, will they immediately know it was us?
- if we kill someone without any witnesses, will someone know anyway?
- when we use a bow out of a “hidden” spot on an enemy, will the enemy know where we are?
- will a one hit strike be lethal, when being unnoticed while sneaking/crouching?
- when beeing detected, do we have a chance to hide again by cutting line of sight?
There are for sure more mechanic for having a nice stealth experience but I think this lists the most important things for being able to stealth properly.