Have you ever think if the subscription model just gone away?
It's a old system, new MMOs don't need this mercenary model. We have gw2, same generation, never have subscription (many others: BDO, ESO, SWTOR). The new generation is buy-to-play or free-to-play.
In my opinion, blizzard must remove the pay-to-play (we already buy the game, is it reallly needs pay a "rent"?)