And the throughput change to divine aegis for only prayer of healing is the right way to go without affecting pvp, and hopefully takes a jab at aegis stacking in pve. But lowering the cost of PW:S will also lower the sunk cost of that shield before a rapture return. So even with a slight throughput loss to PoH, the amount of mana you'll be swimming in will allow for some "interesting" play. For one, you will still be able to snipe all the heals in LFR with PoH spam if you had more mana. But also, you'll be able to spam more flash heals and pw:s, which to me means you can do a lot more Strength of Soul and (as someone already mentioned) Divine Insight play.
So PVE Disc will be your go to for really threatening mechanics that need absorbs, really heavy tank healing, or dps while healing. Holy will be breaking out of the party restriction aoe, have bigger but longer cooldowns, and will bring the raw throughput. These are my early thoughts, subject to change the more personal testing I do on the ptr.