There is an interesting discussion over at Piste Hors about whether or not off-piste hazards should be marked. This follows the death of a 17 year old British rider who fell 70 metres over a cliff in the Cote Brūne sector of Meribel last week.
I don't think anyone should expect such warnings when riding off-piste and nor should any ski area be expected to undertake such an onerous responsibility.
What is needed is better education about the dangers of off-piste riding which, to the uneducated, can often seem so benign especially when near to a marked piste and heavily tracked.