Switching genders and factions of characters is another feature that Blizzard said will never be implemented, but of course after yesterday's news, who knows -- the last big feature that Blizzard has yet to add to the game is a brand new faction (the two expansions so far have given us new races and a new class), so if they do introduce a new faction, maybe they will allow us to fundamentally change our characters somehow. And the last bastion of change, the thing that Blizzard has implied that they'd never ever do, is allowing cross-faction communication or even grouping.
Which brings us back to some concerns from players yesterday -- the PvE-PvP gap was one of the things that made World of Warcraft stand out as a game, and by removing it, Blizzard has made their game less individual, and more homogeneous with everything else on the market. It seems unthinkable now that they'd ever allow Horde and Alliance to chat with each other or group together -- that war is what makes this Warcraft. But after yesterday, who knows what other walls Blizzard will be willing to remove to "provide players with more mobility and freedom to play with their friends"?