It's so hard to say, but I'd vote for a pure Heinz 57 :).
Seriously, when dogs are the result of several generations of random mixed-breeding, they tend to end up with a shorter, light brown coat and medium build. Look at any of the pariah (stray, semi-feral) dogs that live around various 3rd world communities, or many of the recognized pariah-type "breeds" such as the Canaan Dog, Carolina Dog, Basenji, Australian Dingo, Telomian and New Guinea Singing Dog. Canaans and Basenjis come in other colors but their most common color is a yellowish-reddish color.
Nondescript pariahs that live amongst primitive and 3rd world countries all bear general resemblance to other pariahs in other areas. Generally speaking after generations of random mixed-breeding, the dog's form and type reverts back to that which is most useful for survival- brown, yellow or reddish coat that blends in with grasses and vegetation, medium size for speed, agility and less of a caloric intake need, small, often erect ears and an upright or curled tail.
Not saying he's a pariah or a dingo/feral dog (doesn't quite have the look of anything recognizeable) but quite likely he's the result of a lot of random breeding. He's a pup so it's hard to say for sure- I knew someone with an Akita/Chow mix pup who looked similar to him, so I could be wrong. He might be a cross of just a couple different breeds. Time will tell....he DOES have big paws so he might end up being a bit bigger than "medium sized". Either way, he's a cutie.