They could either tweak Blood Tap a bit and put into a new Tier with Plague Leech and another similar ability (Probably Tier 1, that's another rubbish tier, 2/3 are crap, Unholy Blight is good but it could be so much better if perhaps it was one of the new damage talents.), or just give us back our old Blood Tap.
I know this isn't really the place, but since I've been talking so much about how I'd fix Death Knights etc, I actually had a go at coming up with some changes to the talent tree. Mostly just for one certain talent that I'd love to see Death Knights get, straight from the big man himself.
http://mop-talent-grid-maker.appspot...&gridId=137001