In Blade & Soul, some classes are race exclusive but in the future the game will break the restriction and add one additional class to 3 races in the game (Lyn has got Summoner so my guess is Lyn won't have new playable class). Blade & Soul's Chinese publisher Tencent Games confirmed this to 17173.com although they didn't specify which new class will be added to which race. Imagine you can play Gon Summoner or Jin Destroyer or Yun Kung Fu Master.
The game will launch in NA and EU with existing classes. However, Lyn will have the newly added Summoner class along with Force Master. Gon's playable classes are Destroyer and Kung Fu Master. Jin player can choose from Assassin, Blade Master and Kung Fu Master while Yun can play as Force Master and Blade Master. You can check out details at B&S official site.