Before the Nexus 5 was released and Android 4.4 announced, we thought that maybe Google was setting up to release the "Google Experience launcher" into the Play Store. After the Nexus 5 was released, it looked like the launcher could come as part of the Google Search app updates. But, Google has confirmed that at least for now, the Google Experience launcher will stay as a Nexus 5 exclusive...
Source: http://www.phonearena.com/news/Google-Experience-launcher-staying-as-Nexus-5-exclusive-for-now_id49114
Source: http://www.phonearena.com/news/Google-Experience-launcher-staying-as-Nexus-5-exclusive-for-now_id49114