I don't mind open endings... I just didn't like this movie much.
It lost me for a few reasons...
Killing of all the supporting characters.
The one character opting to stay behind... and apparently a strong willed character despite an injury.
The death defying leap from the cliff into the trees.
Taping little, tiny broken bottles and a knife into your hands to battle a wolf. C'mon... even the knife would have issues getting in there with fur and skin - not mention a large, vicious wolf attacking you.
But, the big one:
The wolves at the the base of the cliff, apparently waiting for the survivors.
I can suspend belief, I like movies with 'leaps of faith,' and huge plot holes, loops, twists, fate, kismet, coincidence and what have you... but, I was already on the fence due to the unlikable characters, despite going in wanting to like this movie.