Make Shadow orbs default baseline resource for Shadow priests (read on, dont flame me yet).
Replace Void Eruption with Devouring plague (i know it is already in, but lets not speak about it).
Do the scaling on numbers so it works fine and align talents revolving around Insanity and voidform to work with Orbs too. Add something to spend Shadow orbs on, next to the DP.
Replace Surrender to Madness with Void-something talent. It would replace the Devouring plague with Void eruption and Shadow orbs with Insanity.
Can be done other way around, so Surrender to Madness would be replaced with Devouring plague and Orbs, when default resource would be Insanity.
Dead talent revived, Everyone pleased.
Perfect.
It an idea, so please don’t kill me for no ultra-detailed answer with dozens of arguments and rotation background.