Seeing as how Kil'jaeden's Cunning is being changed in 5.4, I wonder why they would not just give us the ability to cast the three specific spells on the move baseline, and make Kil'jaeden's Cunning something else?
Maybe Kil'jaeden's Cunning would be "Your critical ticks of Immolate have a chance to reduce cast-time of chaos bolt by X%, your critical ticks of agony/ corruption have a chance to reduce the cast-time of Haunt and/or Unstable affliction by X%. Since Demo already has molten core passive, I'm not sure what would work out for Demo, maybe crit ticks of corruption will generate X% more demonic fury?
Also since ember generation through RoF is nerfed and they have not yet given us a "fix", I have two possible ideas.
1) Change backdraft to affect the mana cost and cast time of Incinerate and the mana cost and crit chance of fel flame. This would make fel flame possibly a better choice when Fire and Brimstone is activated.
2)Allow fire and brimstone to affect chaos bolt and let the chaos bolts cast while fire and brimstone is active generate embers. I don't know if those chaos bolts would cost 2 embers to cast or not.