TBH I don't think we have even close to enough info about them to make any real decisions about something like that just yet. Still way too many questions such as....

1. Death Grip - What will be the CD/cost of it? Will it work on heroic elites? Will it work on bosses? What will be the range?
2. Death and Decay - Is it channeled? Is it more like consecration in that it occurs wear the DK is standing or will you be able to target a area much like blizzard or rain of fire? If the mobs are feared are they going to run all over hell and back potenitally pulling additional groups?
3. Dot's - Are they instant cast? are you able to cast them at range? or will it be more like a melee cast much like say judgement? Are they going to be signifcant sources of damage or less dmg but more utility added into them?

Plenty of other questions still to be anwsered on not just DK's but all the other classes. From the sounds of it, it sounds like quite a few changes are going to be made to all classes.