This Pay-To-Win stuff being posted is getting ridiculous. There's no indication that the in-game store is coming AT ALL for the majority of WoW players in the NA and EU markets.
All this uproar started with an xp potion datamined out of a recent PTR patch. There wasn't any official proclamations of a new store option coming for NA/EU. If anything is true, this in-game store is likely for the Asian (China/Korea) market. They have lost lots of subs over there, and its mainly due to the difference in how many players in that market do their gaming. In the US or EU, the average gamer plays from home, on their own internet, so the current model of a monthly sub works. In Asian markets though, many gamers are still using net cafes (which are almost non-existent in the US) and playing by the hour. The most popular MMOs over there are now F2P with game stores for items enhancing their characters. In other words, they get the sub fees out of the store purchases for gamers that tend to do shorter but more intense marathon game sessions.
TL;DR - NA and EU players might never see an in-game store, and its pretty clear policy that Blizzard wouldn't have players pay both a monthly sub and for items to stay competitive from a store. Most likely players are just jumping the gun due a datamined item meant as an option for net cafe focused gamers (China/Korea).