If i'm remembering correctly, it's not entirely the meego successor. Sailfish is a new project from the people who worked on meego, but the actual meego project turned into Tizen.
N9 'meego' was Harmattan, the direct descendant of Maemo 5, planned before the link-up with Intel to create Meego 'proper'. Harmattan had some backported compatibility pieces to make it nominally Meego compliant, but it was really Maemo 6.
Tizen came from the Meego proper project, which was more Moblin than Maemo.
This is what happens when you let marketing... do anything.
