xkcd

And, since we’re all cannibals now, what portion of the hucows is going to be reserved as hucow food?

I think this is where your farming idea falls apart (or becomes identical to the problem discussed in the video). You can't sustainably farm animals without an external energy source. The reason we farm herbivores and some omnivores is that it's possible to feed them with grass (or whatever processed awfulness passes as grass nowadays). When we do farm carnivores for some reason, we feed them with meat harvested from herbivores.

A fully cannibal-based farm is simply impossible because even if humans were perfect at turning food into muscles on their body, there wouldn't be anything to (sustainably) extract from the overall farm system, since there wouldn't be any extra energy/muscle mass/whatever going into it. Also, humans are very very not perfect at turning food into muscle mass, and waste most of the energy that came into their system on stuff like breathing and heartbeat and other metabolism. So, if the requirement is that all humans are cannibals, the only thing left to do is to farm non-sustainably, i.e. extract meat from the system as it runs out, feeding hucows with other hucows to keep at least some of them alive, but eventually you will run out of hucows (which is, once again, pretty much what's discussed in the video).

Alternatively you could claim that "hucows" are not "humans" per se and feed them with non-hucow-based food, in which case it could probably work in a fairly similar manner to modern-day pig farming but on an even larger and more horrifying scale - pigs are quite similar to humans in many ways. Sans all the pandemics that would eventually happen due to cannibalism, of course.