I believe the plan is that there will be no "normal" campaigns existing anymore. Gray Host will shift to the planned new mid sized Cyrodiil map. And together with 2-sided 8 man Battlegrounds they will be sweaty player hotspots for PvP. And Vengeance will replace Grey Host completely. Vengeance and old 3-sided Battlegrounds will be the normal PvP areas for normal players with a life as vanilla ESO once was. And hopefully Vengeance will never get Subclassing or Scribing ever (Wishful thinking would be no-proc sets, as well). That is at least the direction i see PvP is going and the one that makes most sense imo.
I’ll raise you one, let’s add Subclassing to Vengeance.
I wonder how (if at all) Vengeance skills will be changed with each class balance refresh. I think Vengeance as it is would be the best environment to have Subclassing in, but maybe that'll change after the rework to each class.