Obviously, anthropologists classify the nomadic pastoralism of Mongolian peoples differently from the hunter-gatherer groups that characterize the ancestral milieu of the Paleolithic.
However, in some ways, nomadic pastoralism has more in common with hunting-gathering than with sedentary pastoralism. Although contemporary Mongolians are living in a partially modernized state and trade and purchase for modern goods and foodstuffs, my impression from an initial shallow reading of Mongolian history is that the steppe lifestyle was fairly unchanged from its introduction up until the 20th century and that today's nomads still have quite a few similarities with their forebears. Their nomadic pastoralism did not always include the raising of domesticated animals for food. They continued to hunt. The Tsaatan reindeer herders do not eat the reindeer except in extremity, and I imagine the reindeer are only partially domesticated. The extent to which they gathered was severely limited by the climate. The accumulation of belongings must be very restricted for nomads, more akin to hunter-gatherers I would imagine than sedentary pastoralists/agriculturists.
Although there are people in cold climates that are more pure in hunting-gathering, I wonder how difficult, in the pre-modern world, it really would have been for Mongolian nomadic pastoralists to convert to a model based more purely on hunting? Would they have been able to more or less maintain their lifestyle?
I think the interesting question here is not so much about how food is obtained as about population density. The Mongolian steppe peoples maintained a very low population density. In terms of the number of available calories the steppe could provide in animals, I wonder if the population was comparable to the density maintained in hunter-gatherer groups.
If you see Mongolian nomads as more akin to hunter-gatherer groups than to farming/ranching agriculturalists, the history of the Mongol peoples really changes your view of ancestral man.