No. The article was most likely referring to the final patch before Pandaria where Hellscream is blamed for a disaster and both factions lay siege to the horde capital (I can't spell it) to arrest/execute him. The beta suggests the he isn't killed and remains warchief but to answer your question, no.
The horde is composed of the more self serving races but it depends on who you play.
Basically this is what is going on. Hellscream has always believed that the Horde should rein supreme over the alliance. With Thrall being gone dealing with this Deathwing situation, Garrosh gets put into the War chief of the horde position. Shortly after the Alliance and Horde defeat Deathwing, Garrosh orders an attack on the island of Theramore.
Which coincidently is the home of one of the most powerful mages in Azeroth, Jaina Proudmore. She seeks out Thrall and says that war is inevitable if he cannot stop Garrosh... this is all I know but basically the Alliance and the Horde team together to rid of Garrosh... I do know that this storyline is going to tie into the changes that they make with World PVP. Should be fun :)
I know that there is a huge Sha world boss in MoP now that guilds have raided already on the beta, which is awesome. Reminds me of Doom Lord Kazzak, I'm glad that they are bringing a world boss back. Hopefuly there will be more to follow.