hm, i wouldnt mid if they would add arena's. But i preffer some kind of PvP missions with raiting. They will add Warzone's with raiting if im right, not 100% sure.
though, i like the Warzone's they got atm, especially Huttball! It's very fun to play, and when u play with friends, u can dominate with teamwork.
so i wouldnt mind if they would add arena, but i dont want it to be the main aspect of the whole PvP experience. Preffer the warzones! =)