The main issues with Enhance for example are core to how the spec is designed to function, in that case they'd have to introduce or revamp an existing talent into a sort of "bandaid" fix to alleviate the issues with the feast or famine, pendulum on crack type of gameplay which just means that you're hardlocked into ONE talent.
Same with spriests, the spec itself doesn't function properly and needs to be reworked from the ground up.