Let me throw in some thoughts on domestication.
First, the fox would be a terrible species to try and domesticate. The creatures are relatively solitary by nature, have no inherent social structure, are endlessly opportunistic predators/scavengers, are subject to predation and are therefore flighty and easily agitated.
The fact that someone managed to produce a domesticated or even semi-domesticated fox, even after forty generations, is nothing short of remarkable. I would have said it couldn't be done at all.
Could the Bison be domesticated? I dunno. I've been up close to those buggers, and they're big, nasty bastards, very unpredictable, rather high strung for their size. I'd rather try domesticating moose before trying Bison. Moose seem to have a better temperament.
It seems to me though that we're all being a bit doctrinaire on the subject of domestication. Let me make a few observations.
In thinking through domestication and domestication events, one thing that occurs to me is that for the most part, domestication of draft animals seems to follow after organised agriculture, and often significantly later. Societies seem to need to have mastered farming for at least a few thousand years before they get around to domesticating big hauling/draft beasties.
This actually sets up an interesting catch 22. Agriculture tends to occupy the biological resources of a region, and the increased population provided by agriculture generally means that the local landscape gets hunted out. So the problem is that all the good species for domestication tend to get hunted out before they have the chance to get domesticated.
So for a domestication event to occur, there must be biological or geographical factors that preserve the wild species in something like at least occasional proximity too agriculture cultures.
So, in the case of water buffalo, you've got a critter moving in and out of marginal agricultural lands, the camel you've got a creature of deserts at the edges of agricultural territory. The horse is domesticated in Kazakhstan, probably open country migrators passing the edges or agricultural territory. The llama inhabits the Andes, so likely is protected by hill country.
It seems to me that on this basis, there are only ever going to be a few relatively narrow 'interface' zones where both agriculture and successful wild populations are going to overlap, and where domestication events take place.
Another observation is that while domestication events are rare, by their nature, they likely spread real fast. Again, I'm confining my comments to the large draft animals. I haven't seen any formal studies as to how fast a species spreads after domestication, but my impression is that its usually rapid and pretty much through the viable habitat of such an animal.
It seems to me that because Agriculture happens first, perhaps thousands of years earlier, and has spread widely out to the interface areas, then there's essentially a ready made highway for proliferation. Once a species is domesticated, it spreads widely through the agricultural economy that hosted it, allows that agricultural economy to spread more readily. And it seems to jump easily to adjacent agricultural economies.
But that rapid spread has a consequence. I'd argue that each domestication event tends to disable other potential domestication events. Once you've got oxen, why bother to try and domesticate caribou or pronghorns or hippopotamus.
This doesn't mean that every species is hypothetically domesticateable (although the fox example is suggestive). But what it does mean is that likely a lot of domestication candidates in the environment lie fallow or go undomesticated - either because they're wiped out by incoming agriculture, or because prior domestication events take up the niche.
So, I don't think we should close the door on the possibility of other sorts of domestication events, as in Jared's 'Red and Gold' timeline, or threads like this that speculate on possible North American domestications.
Does this mean that the Bison is a likely candidate for domestication? Hmm. Well, it seems to me that under this hypothetical, the bison would have to be shoulder to shoulder with an agricultural society, but not obliterated from the area. I don't think that in the case of bison that the sort of 'interface territory' ever existed. My impression is that agricultural societies and bison were far apart, and that the cultures closest to the bison were hunter gatherers, or at best hunter gardeners, who wouldn't be the right people to make it happen. I think you'd have to mess about to put the right kind of human culture in the right proximity to bison to have a chance. I don't see it as being all that stable a situation, and you'd need some longer term stability for the interface to work.
On the other hand, North American mountain sheep might do the trick, if they were in the right place. Or marsh ungulates like the moose might.
I'm kicking around Giant sloths even as I write. Hmmm. I might go and do interesting violence to someone's not very active timeline.
Another random thought on domestication - is it related to parasitism? It seems to me that the current theory on the domestication of cats and dogs is that they were essentially scavengers at the edges of human culture. With our garbage and our pests, we supplied a ready source of stable food, so the ancestors of dogs and cats just kept hanging around and hanging around....
Looking at agricultural societies, they're likely to produce some relatively eatable goodies, particularly if you're a big ass herbivore. So perhaps we've got something similar happening here. The human presence creates specific food opportunities, so they just start hanging around and hanging around. I don't know that this creates domestication itself. But an inbuilt familiarity with human presence, a tendency not to panic around humans, probably relative freedom from non-human predators and thus less ingrained nervousness.
The role of opportunistic parasites may be a lot more significant to domestication than we assume. And this itself offers up some interesting notions.
Any marijuana farmer can tell you what a pest deer are. Canada Geese are prone to mooching off humans and will stop migrating. Bears are common animals hanging about garbage dumps in rural areas. Are we witnessing pre-domestication events? Or pre-domestication situations?
Of course the problem is that we've already got plenty of domesticated fowl and waterfowl, thank you very much. There's no apparent niche left for the domesticated Canada Goose. As for bears, what would anyone do with domesticated bears - I'm trying to think of what bears might be good for, and basically they're screwed, on the low end, dogs do all that stuff better, and on the draft end, regular draft animals are more efficient.
Still, it might be possible to imagine a society with extremely peculiar needs domesticating bears. Or possibly a society which didn't have any good herbivore or canine forms.
Anyway, just some thoughts. Remember, this is AH, let's not get too doctrinaire. Jared Diamond and his ilk may be smart guys, but all they really do is best guesses.
A final bit of thinking