Originally Posted by Pasco

Source: World of Warcraft - English (NA) Forums -> Upcoming Changes to Mana Regeneration

Summary:

- Regeneration while not casting (outside of the “five second rule”) will be decreased
- reduce mana regeneration granted by Spirit across the board
- boosting the effects of talents such as Meditation

And:
"We are also taking a close look at clearcasting procs themselves. One likely outcome is to change them to an Innervate-like surge of mana so that the net benefit is the same, but healers won’t shift to out-of-casting regeneration so often. "

I'm very interested in the exact numbers here, but I hoped they wouldn't touch Spirit/5SR but instead nerf Intellect and it's synergy with effects like Replenishment. That a nerf for mana regeneration would come was obvious.