I don't know how well linguists have figured out how to estimate time depth; the fact that a small tweak in the methodology (compared to Bouckaert et al.) results in a 3,000 year drop in the estimated age of the PIE split does not add to my confidence about the robustness of this field. Regardless of which hypothesis one accepts, the PIE split occurred thousands of years before the first written monuments in any Indo-European language. For the time being, the ball is on the other side of the court, which may accept this finding or come up with another tweak in the methodology that gives yet another date.
In any case, accepting provisionally that the Chang et al. date is accurate then it falsifies the Anatolian farmer/IE language hypothesis. So, steppe aficionados can declare a partial victory, because there is one less opponent to worry about. Falsification of the Anatolian first farmer hypothesis is not a complete victory, as the PIE urheimat question is not a boxing match between Kurganists and Anatolianists, but rather a mêlée with many players holding on to their swords. So, if you're willing to believe that the methodology is mature enough and they finally "got it right", you need only find a PIE split around 6,000 years ago, but you need not find it on the steppe.
ANCESTRY-CONSTRAINED PHYLOGENETIC ANALYSIS SUPPORTS THE INDO-EUROPEAN STEPPE HYPOTHESIS
Will Chang et al.
Discussion of Indo-European origins and dispersal focuses on two hypotheses. Qualitative evidence from reconstructed vocabulary and correlations with archaeological data suggest that IndoEuropean languages originated in the Pontic-Caspian steppe and spread together with cultural innovations associated with pastoralism, beginning c. 6500–5500 bp. An alternative hypothesis, according to which Indo-European languages spread with the diffusion of farming from Anatolia, beginning c. 9500–8000 bp, is supported by statistical phylogenetic and phylogeographic analyses of lexical traits. The time and place of the Indo-European ancestor language therefore remain disputed. Here we present a phylogenetic analysis in which ancestry constraints permit more accurate inference of rates of change, based on observed changes between ancient or medieval languages and their modern descendants, and we show that the result strongly supports the steppe hypothesis. Positing ancestry constraints also reveals that homoplasy is common in lexical traits, contrary to the assumptions of previous work. We show that lexical traits undergo recurrent evolution due to recurring patterns of semantic and morphological change.