A lot of truth in that post.
The world changed and internet gaming changed both in platforms (100 million iPads sold) as in TIME that people want to devote to on line gaming (fast satisfaction, short sessions, "awesome" graphics not possible in MMO's due to the masses of information of hundreds of players in one place etc ...).
However this is a natural cycle. All I know is that WoW was an awesome long term experience for dozens of millions during a time in their lives.
So much so that all those who left ... STILL come back to forums and discuss the game with a rarely seen passion.
I also think that the new non MMO games lack things you can still find in WoW. Like free to discover sandboxy elements and go for extreme rare and hard achievements, progression that never ends, ...
It is also foolish to look at your own life cycle and experience it as something universal. There are trends but even now there are new people (young or old) that just start to discover WoW.
The sad fact is that the copycats didn't bring enough innovation in the MMO industry in their ever failed trial to copy WoW and get to those millions of WoW subscriptions, which made for VERY stale copycats.
But do not underestimate the return of MMO play in the future. Perhaps Destiny is already a good mix of shooter/long term play as another kind of on line experience with eternal progression.
tldr: WoW was/is a once in a life time experience for too many of us. I played video games for the past 35 years and looking back WoW has a very unique standing in the hundreds of games I played. I am quite sure I am far from the only one.