Sith Healer? Hmmmm me thinks you do not understand the nature of the Sith.

Seriously though, there is a big question surrounding any thoughts on pvp class balances. It doesn't look as if Bioware are overly concerned with having a direct opposite class for each faction. They seem far more concerned with sticking to the lore of star wars and creating a highly immersive story driven MMO. Perhaps they will work sith healing some other less obvious way? Who knows. But I would certainly not be looking for direct class parallels.