That's such a bummer if so. It sucks wanting to play as one race but all your friends are on the other faction. It also doesn't work as well when you have a lower population game. And let's face it, that's what this game is going to be. It's not going to get WoW numbers, so designing a game expecting that is foolish.
1. Friends don't let friends play apposing factions. On Vanilla WoW my friends and I had a Horde Server and an Alliance server. Easy.
2. This game will not be "Low population". Stacking any game up against WoW numbers and calling it "Low Population" is silliness. A games total population does not reflect SERVER health as each server has a population cap. WoW used to be 2500 players per server (I think). Having a lower total population in an MMO only means the game isn't making as much money. Population arguments about game play are irrelevant...especially if an MMO plans for server merges ahead of the games release.
3. Player friction matters: When people see opposing faction players in a PvP game....it should be exciting. It should get the heart pumping with the anticipation and of combat and fear of loss. When a player sees the opposing faction they should NOT be thinking..."I wonder if they want to be my friend."