A graphic doesn't say anything "as in". If it's 0, it means 0. Values are only rounded on this graphic on an M scale, of course, you don't simply round from 1 to 0 when the maximum value is around 12.
This is where 1m (or 999.999) would be:
The most you can argue is it is a trend curve, not predicted values, but even so he wouldn't be "wrong" to disagree the tend curve is wrong.
On topic: As mentioned before, it won't simply drop from 7.5M to 0 the same way it got up from 0 to 7.5M.
The most likely scenario is it will keep losing subscriptions, slower as time goes by, with small increase bumps on expac/patch releases and/or popularity spikes. It will probably remain almost stable from anywhere between 1M to 4M for a few more years, at least until Blizz (or some new revelation) releases THE wow successor (and by this I mean something like WoW2, or Titan. Something that would make people swap from WoW, not necessarily even something subscription-based) or they are no longer able to pull expansions out of their arses in a convicing-enough fashion.
Like linked before, this:
NOT a symettrical arch, but something like this (not trying to predict specific numbers, just the trend of the curve):
It's just a matter of at how many subscriptions will the losses become less significant, and for how long will it remain so, and this depends on many many variables that we can't simple predict accurately, but it will almost surely survive above at least some 4M past 2015 depending on how well WoD does, and considering the next expansion will likely be Burning Legion themed, it's unlikely it will have huge drops on the number.
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1st table:
Source for those numbers? Those don't really seem to match most mainstream information
Even if they are truthful, and you care so much about sub/player numbers to define how well a game is doing, is Club Penguin really comparable to pretty much any game below Wizard101(which I never heard of before)?
2nd table:
That's free-to-play (micro-transactions) earnings alone. Here's another table:
According to those 2 tables (source chosen by you) WoW not only is #7 on micro-transactions despite being the most subscribed, and had above 1 billion of revenue in 2013 (subscription+micro-transaction). More than any other game in any of those tables.
And a graphic:
I'm sorry, but I find it idiotic to say SWTOR was a failure, for instance, much less than WoW is dead or "only a bit more popular than SWTOR". There are THOUSANDS of small and/or local brands who live along side mainstream global products. Are they a failure just because they aren't number 1? Is a local actor that manages to make a living in small movies a failure just because he isn't viewed by as many people as a holywood actor?
You're stating that the game that's likely the #1 or #2 making the most revenue in 2013 is dead. It is only (likely) bested in revenue by GTA:V, which released in 2013.
If 36% of the subscription-based market share plus being #7 on free-to-play earnings is being dead, every single bloody game in this world is dead. Add to the equation that WoW is based on a 10 year old engine (there's only so much they can improve with expansions) and already concluded the storyline that driven a lot of players to it (with WotLK) and it's pretty much a phenomenon that is still holding close to as many subscriptions as the maximum Vanilla ever had.
WoW number of subscriptions peak was a popularity spike (in the same way as the popularity spike of Flappy Bird), it was not because the game was inherintely better then, or better than the others in the genre, it just happened. It offered the right things at the right time with the right exposure.
Now it's been 10 years, many of the players (at least above a certain current age) that wanted to try WoW already have. Many players already played for a while and got tired of it, moving on. There now remain the players who never left, the ones who started more recently and are still enjoying it, the ones who keep coming back every now and then to check new content, and the ones who are still joining in for the first time. It's far from dead, and it WON'T be dead while it's profitable, which it will be for years to come even if it eventually becomes F2P.