Yeh, after teasing it so many times, and then making the corporation rubbish by faction fighting again, finally they are going to change this. I say good riddance, the factions in wow have served the opposite effect for the gamestory and interesting developments, they've limited it, and made for awkward behaviour that often comes off as bad writing, making a lot of talented writers look like rubbish and undermining the integrity of the vast majority of the story.
All of a sudden because one group is on one faction, they completely forget about everything in their past, sometimes even forget how to communicate with others, impossible walls of hatred just spring up where there was no such intensity previously. Inventing new animosities that just feel wonky and don't make sense in terms of previous partnerships, then leading to previous lore being recast making it look like a retcon or changing stuff and fantasy people really really liked, pissing off the player base some more, just to drive a wedge because people in one faction must absolutely hate the other and have little to no relationship except for story devices which demand it, then go back to completely forgetting thir arse was saved not that long ago, by the same people that all of a sudden are so eager to chop them up for stupid reasons that don't make sense for a supposedly intelligent people.
And so it goes on, limiting everything, but the game dproduces unwilling to invest the time in the game to make it make sense and iron through, because that's just not the format of the game.
So the best decision is to change that dynamic entirely for the general lore. Once Arena and bGs became same faction, it quickly became clear that the people loving fighting most didn't care what races were their friends, they had no trouble fighting same faction team, and unlike other games, blizzard made no effort to present same faction battlegrounds as training exercise, just ignored the fact that I twas the same faction.. so if they're not willing to do things properly, why bother to keep maintain the faction divide when it's so farciacal..
one faction each race kind seeking it's own ends makes for far more interesting inter-relations where a player can really choose how he will operate.