“Assyrians, Armenians, Turks, etc. If I’m not wrong, Chromo-Painter and fineSTRUCTURE analyses at the Dodecad Project pretty much illustrated the same.”

I agree that there is probably significant shared ancient ancestry between the groups you mention. However, I do not believe it has been established through either of the two programs you refer to. At least as far as Assyrians are concerned. Heat maps from the most recent Dodecad fineSTRUCTURE and Chromo-Painter runs, respectively, below:

Assyrian populations are 0, 11, and 19.
1. http://2.bp.blogspot.com/-zz36Fb6G_0Q/T1x_B9dga0I/AAAAAAAAAuc/BZIRmkQFI6Y/s1600/heatmap.png

2. http://4.bp.blogspot.com/-zioOVQU3E4Y/T1UE8-vxJyI/AAAAAAAAAt4/r3y_IV1uvwI/s1600/heatmap.png

Among whom?

Yes. But the North European genetic overlay you mention is higher in Turks (even excluding Balkan Turks) than not only the one in Armenians and Assyrians but also the one in Kurds and Iranians.

AV, which Northern Middle Eastern neighbors do you mean specifically?

This strongly points to the fact that both Iran and India were already too thickly populated by farming groups for a semi-nomadic/pastoral group like the Indo-Iranians to penetrate the region and leave substantial signals of their genetic signature, while Afghanistan, Pakistan and North-Western India received more of it, as evidenced by the ~10-15% North-European admixture in the latter regions, which should be a good predictor for Afghan Pashtuns as well. Which is why probably why the generic Indo-Aryan speaking populace of India and typical Iranians have about the same Northeast European admixture. In addition to that, the Yunusbayev et al. Tajiks are also ~20% North_European.

The Kalash, Pashtuns, Kashmiris, Punjabis, Rajasthani upper-castes and Uttar-Pradesh upper castes all seem to have around the same percentage of the North-East European component. Of course, they differ in their percentage of other West-Eurasian components, thus making the Kalash and Pashtuns the most West-Eurasian of the mentioned groups and the eastern Gangetic belt upper-castes the lest. The Eurogenes Hunter-gather vs. Farmer ADMIXTURE test for example pegs the Baltic hunter-gather score of the Kalash at 13%, the Pashtuns at 12.8% and U.P Brahmins at 13.72%. DMXX at the Vaêdhya research blog takes note of a similar trend in his write-up on the intra North-Euro Eurogenes analysis;

“One curious phenomenon is the similar West European-North Sea-Northeast European component proportions across the Turkmen, Uzbeks, Kyrgyz, Pathans, Uttar Pradesh Brahmins, Altaians and the Uyghur.“

As you’ve gone onto hypothesize, in the case of North-Indian upper castes; the Aryans, after sprinkling their genes around in Northwest South-Asia, very likely pressed themselves into a group that was to become the upper castes of North-India once they travelled further east (North India proper and the like) – in the sense that they likely gave their culture to an already pre-existing upper class and thereby were absorbed into them, albeit leaving an appreciable amount of genetic impact, too. Thus, the Northeast European fraction is relatively uniform throughout not only Indo-Aryan speaking Brahmins, but also ethnicities further west in general, while the other main West-Eurasian components (one centered in Balochistan and the other in the Caucasus) have a west-east cline.

All in all, the genetic demographics of South-Asia strongly points out to the overwhelmingly increasing validity of the Kurgan hypothesis and the Pontic-Caspian dispersal point of proto-Indo-Europeans.

PS. I’d also like to note that the Kalash don’t seem to be an Indo-Iranian relic as previously thought. They simply seem to be an inbred and genetically homozygous version of their Pashtun neighbors, going by their ADMIXTURE results per HarappaWorld and Eurogenes hunter gatherer vs. farmer test. I think this inference was made by Razib himself based on a phylogenetic tree by Uğur Hodoğlugil et al. showing the Kalash clustering with the Pashtuns and somewhat close to the Burusho.