This article suggests that the yeti may be an unknown species of bear. As some bears stand erect and even walk a few steps, it is plausible to consider a species that does so more often. Certainly a bipedal stance would be one way to deal with the snow and to reach food overhead. Another interesting fact is that some species cope with cold weather by adapting a more compact form, such as shorter muzzle, ears, tail, etc. That could make its face look more apelike even if it is not a primate. Bears are also pretty smart, and while some are pugnacious, others are really shy and hard to find. It's not hard to imagine one with the social tolerance of a snow leopard.