I realized that we didn't discussed much the Proto Indo European homeland theory proposed by Lazaridis and Reich. Well their proposal is quite simple.
They propose the PIE homeland in West Asia. More specifically in historic Armenia and around. From there two branches splits. One moves to west, which become the Anatolian branch. Hittite and Luwian are the daughter languages of this branch. While the another branch moves to North and creates in Steppe various pastoralistic cultures. The most prominent of them are the Yamna and CWC. Sometimes later 4500 years ago a group of Yamna people returns back to Armenia reintroducing a new branch of IE language which will become the Armenian. This theory explains why Armenian has common linguistic features with Greek and Indo-Iranian. But less with Hittite. See the picture at right.