According to this article and others I found on the subject, it is going to be Sailfish based (thus, heritage includes Linux, Mer, MeeGo, Maemo, Moblin, and wha

According to this article and others I found on the subject, it is going to be Sailfish based (thus, heritage includes Linux, Mer, MeeGo, Maemo, Moblin, and whatever other names it had before; And still shares a lot with Tizen.