We have long had circumstantial evidence that racial differences in intelligence are partly genetic. We know that the races differ in average intelligence, and we know that intra-race differences in intelligence are partly genetic, partly non-shared environment (random effects, measurement error), therefore it is likely that the same applies to inter-race differences.
No one denies that Tibetan adaptations to high altitude are entirely genetic, not cultural, and there are many other race-specific traits which are uncontroversially attributed solely to genetics. But when it comes to intelligence, the obvious inference is not drawn.
Genome-wide association studies are finally identifying specific genes for traits. We can now make accurate predictions about someone's traits from their genome. As individual genes are identified, and these genes are shown to have different frequencies across the races, how will the left react? How is the left reacting?
Denial will continue for a long time. We've had evidence for a long time; why should one more piece of evidence make a difference?
To some extent it doesn't matter. Philosophical obfuscation about the concept of race won't work any more. Ordinary people will be able to see the validity of the science with their own eyes. The leftist obfuscation will be ignored. Ordinary people already want to choose high-IQ, tall, good-looking sperm and egg donors; they understand the truth on an implicit level at least.
Eventually the left will have to adapt its theories to the reality of human genetics. I expect people will realise that "meritocracy" means "genetic advantages", and egalitarianism will attempt to equalise these, either with monetary redistribution, or genetic engineering (state-subsidised embryo selection for the poor, banning embryo selection for the rich, etc).