The announced upcoming paid-service to change your faction will also change recruitment.
It will greatly help casual and specialist guilds (like religious, RP, daylight hour, and late night guilds) because it increases the pool of people they can recruit.
For hardcore guilds, it means they’ll have both more competition for recruits and supply of recruits. This should make it overall easier for top guilds to fill out their ranks. We might see minmax decisions on racials effecting which faction they’re in.
Check the blue post on faction switch. There are no details yet, though.
Personally, I’d love to be Tauren for looks (and a bit of HP), but the guild I’m in is alliance so my DK is human. I wonder if this will cause some guilds to lose people to ‘the other side’.