There is something strange with the numbers.
Just take a look at this chart released in early september.
http://www.finalfantasyxiv.com/Eorze...N_Census_S.png
In an interview some weeks later, Yoshida said, that around the half of the active players (no chars) have finished Alexander normal mode.
I'm pretty shure, the clear numbers have been increased more than a little bit during the census and that interview.
In my opinion there should be at least around 800k active players.
Don't know how many ppl are out there with an active account without Heavensward, but I don't believe its the majority of the active playerbase.
