So lets talk PTR. MMO Champion has the latest build notes up and if you haven't heard by now master of ghouls and night of the dead are changing places.
Unholy DPS specs that rely on a perma ghoul will be just fine since you will still be able to get both talents. Blood and Frost DPS specs that used to dip into unholy to get the perma ghoul are going to go without.
Now we all know perma ghoul without night of the dead is not that permanent since they die to AOE a lot so this may not be as big of a nerf as we think on the surface. That said, I'll leave the hard core theory crafting up to our friends over at EJ. The same goes for Death Strike nerf.
Over the next few days I will replace my hybrid Tanking/DPS build linked on the right with several builds for 3.1. I honestly haven't used my hybrid build in a while. It works great for small guilds in heroics and Naxx 10 but it just doesn't perform well enough to forego the respec costs to change back and forth between dedicated tank and dps in Naxx 25.
The builds I am planning on putting up are Blood Tank, Unholy Tank, and Unholy DPS. The expectation is that you will have dual spec and pick two out of three. I have seen rumors that ebon plague stacking has been fixed but I don't yet have evidence I'd rely on 100%. As soon as I find it I'll pass the confirmation on.