Both the N8 and Lumia are more popular than the N9
Swipe is sexy, but unpractical compared with both Belle and WP
My first "claim" is based on online shops backed up with statistics from Google. The second one is my personal opinion, but one that I know is shared by many others.
My "claims" are all by themselves enough reason to why the N9 cannot be a flagship. Elop also doomed Symbian, but the N8 refuses to die. Why does it refuse to die? It refuses to die because people like it.