does a trolls beats slaying racial work against druids in feral or bear form and if so will it be taken away in cataclysm
Depending on the form, the Druid is considered either humanoid (Caster and Moonkin), beast (Travel, Aquatic, Bear, Dire Bear, and Cat), or elemental (Tree of Life); and thus is vulnerable (or immune) to different spells. This also applies to being tracked.
A 5% damage boost from Beast Slaying against morphed druids hardly a huge boost and Blizzard have shown no interest in removing it previously, or in future due to the limited PvP effect. There is always talk about Blizzard redoing all the racials, but I haven't seen anything to this effect in the Cataclysm beta.