It's certainly possible if you factor in the social and geographic trends and take them to extreme conclusions. It's merely reproductive separation that is required. Whether this be due to geography, climate, mating calls or unattractive IQ isn't really of import. I'll agree that right now the barrier isn't sufficient enough, but I don't think that is what OP was saying (could be wrong).

That said, your point about the time scales is definitely on mark. It would take a long time and likely far more significant isolation than present (don't have numbers). Genetic engineering could speed that up substantially.

Of course social factors would likely prohibit any talk about separate species. From a pure biologist perspective there are many different animal species fully capable of reproducing but are speciated because their natural breeding behavior (or location) doesn't support interbreeding. Using the same measure/definition, one could objectively argue that uncontacted tribes and isolated peoples are a different 'species'.

I personally think scientists need to agree on some fundamental genetic/epigenetic (maybe even microbiomic) markers of speciation and move away from more subjective definitions. Reproductive potential makes sense when looking at speciation likelihood, but I am not sure it makes sense as a definition of different species.