Okay, Shadow (or Priest in general) received a slight nerf today with Shadow Word: Death getting decreased damage modificators.
And we've got the datamine of a reworked Necrolord ability:
Unholy Nova (New) A ball of latent corruption dwells within your target, dealing [ 60% of Spell Power ] Shadow damage or healing every 1 sec. After 4 sec, bursts on up to 5 allies or enemies within 0 yds for [ 169% of Spell Power ] healing or Shadow damage. Necrolord. Necrolord. 40 yd range. Instant.
They said this isn't implemented yet and they don't know if they intend to, but I really like this reworked version and would like to see it go live. This actually sounds pretty good (at least for Shadow).