While its possible humans could speciate into two distinct groups at some point in the future, it hasn't happened recently (100 kya) and it doesn't seem to be happening now. If it were happening we would see two or more distinct populations that didn't interbreed and over time accumulated increasing differences.
These skin colors track most of the evolution we've done in the last hundred thousand years or so, and none of the people from different parts of the globe have any difficulty reproducing with any of the others. If speciation is happening it hasn't happened yet. I doubt speciation could happen given how much gene transfer there was between populations just on foot and boat, never mind planes and trains. Although, speciation does not require physical isolation to occur. See Wallace Effect and sympatric speciation. If there's enough pressure agaist hybridization, human speciation could occur. Think blue collar versus white collar worker and the disappearing middle class.
Speciation has certainly happened with humans before. Not with 'evolutionarily modern' humans, but 'evolutionarily modern' is mostly defined as 'humans since the last speciation event', so that's tautological. But Homo erectus, the neanderthals, the denisovans, et cetera(seriously, there's a lot of Homo species) were all descendants from one common ancestor.
As for the idea that Chinese people are a different species, or descended from Homo erectus? See the geneticist from the documentary who mapped out the genetics of the Chinese population. Archeological and skeletal evidence is easily blurred, but the genetics can't be explained without an out of africa theory.