You know, if you really want something legitimate, go to ffxivpro.com
They keep track of all player characters and award points for every rank gained in any job by that player.

I am ranked 26,700 overall all servers.
Unhealthy as you may call it, i have played the game CONSTANTLY 7 days a week for the last two months,
and prior to that i put in a good months worth of that.
So mathematically, with the game at 11 months now,
That means you can divide 70 hours a week by 3.6,
Lets say 20 hours to keep it non brain imploding.
27,000 people play the game more than 20 hours a week on average for 11 months.
So that's one thing. Obviously there is a dedicated BASE of players, we know that.

What really needs to be tracked is how this base moves.
A player ranked 70,000th in my opinion has not the progress to call active,
though any number of these players may turn into active players.

I'd like to see a tracker kept of these stats to know.
Best understand though, there are no more than about 28-30 thousand people TOTAL who have achieved Physical level 50 in 11 months.
That's ... not a very big number.
I'm not making any death claims, in fact, i think this game has a bright future,
But best to know that we are dealing with SMALL numbers right now.

That said, i do stand by my opinion that server pop on Lindblum has boomed.