This is a world PvP video displaying the damage potential of deep arcane in the new environments in WotLK.
Arcane Potency does not look like it is going to be nerfed at this point and I do believe it will make it to release. It will be very overpowered in situations where there is no dispeller.
Deep arcane looks like it will be relying primarily on instant cast crits while presence of mind is up. As long as you have PoM up you will have 60%+ chance to crit and you will not have to worry about spell pushback, LOS, or counterspells nearly as much. It is a very easy spec to play, and with Ice block being trainable it still has great survivability.
Please also note that the majority of players in this video are unskilled and undergeared and I understand this. It was incredibly hard to find players to test out the new spec with in a random pvp environment. I also made the effort to come out with this video as soon as I could, I really wish I could test this out on better players, but i'm sure the results would somewhat be the same.