Blizzard really shocked us all yesterday with the PvE to PvP transfers -- we'd been told multiple times before that it just wasn't a possibility (and Blizzard even got in trouble for doing it for some of their friends). So a lot of players are wondering: just what other current taboos will Blizzard give up in the future, for either gameplay or marketing reasons? Cross region transfers is one idea that's come up on the forums, and Blizzard has (not surprisingly) turned it down, claiming that with the current architecture, it's not possible. Bringing one forum poster to respond that "we can expect to see it in about a year."
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"?