It seems that World of Warcraft patch 1.12 is now on the test servers. The major changes that this patch brings are all about PvP: cross-server battlegrounds, and new PvP objectives outside of battlegrounds. Unfortunately both of these new features will suffer from the Horde : Alliance imbalance.
Cross-server battlegrounds are a good idea, because they get rid of the "rounding error". The problem previously was that if less players of one faction signed up for a battleground than was needed to start, the battleground didn't start at all. Which meant that battlegrounds that needed a lot of players, like Alterac Valley, weren't always available. By adding up the handful of players wanting to play AV on each server over several servers, it is now much more likely that at least one AV battleground will be open most of the time.
That pretty much eliminates waiting in a battleground queue, ... for the Horde. Alliance will still be waiting in line a lot. There are between 1.5 to 2 times as many Alliance players as there are Horde players on all servers, and thus the number of battlegrounds opening up is limited by the number of Horde players. So if there are 200 Horde players and 300 to 400 Alliance players wanting to do battlegrounds, all the Horde players and 200 of the Alliance players will be able to play, and the 100 to 200 remaining Alliance players will be forced to wait.
Blizzard "balances" that by the other new PvP feature, PvP objectives in Silithus and Plaguelands. These favor the Alliance, because there are no restrictions to the number of players able to participate on each side. Thus Alliance will "win" these by default, due to greater numbers. I don't really understand what that is supposed to add to the game.