The fact theres to many numerous races on azeroth keeps the players lvling on like "OMGSH THAT RACE LOOKS UBER PWNAGE" and they soon reach that lvl and they see another race they like, thats the way azeroth hooked players. I easily could imagine 3 new races for the server.

Rogue
8 lvls for each skill
knife race only
Starts with 65% speed

Active Camo: Gain 100% invis but loses it when shot or gets near people. The more lvl'd up the more less chance or it setting off.
Sprint: Gain a short burst of speed like 30% exra speed when activated for like 3 seconds and goes more and more time and speed.
Camouflage: Gain 35% extra speed on spawn
Kidney Stab: Stun enemy
Evasive Maneuveurs: Evade 15%
Shadow step: teleport behind the person you put your crosshair on . its an ultimate up to a 30 second cool down and has a 10% to fail/