Now, there are three components of this, two positive (that don't play together) and one negative. So one solution would be remove one of the positives and one of the negative. For example, what if the ability didn't dismiss Eos but only boosted healing spells by 20% and had no Aetherflow? Or gave three Aetherflow but didn't increase healing magic potency? Either of those should still be roughly "balanced".
The Aetherflow is why it's used. The Healing Potency is basically worthless.
Honestly I don't particularly like either of these.

Another possibility is to take a page from New SMN's Aethercharge -> Dreadwyrm Trance -> Summon (Bahamut/Phoenix). In short: Have the ability upgrade into something. The 3 min CD isn't matched by anything else, but we have some options:

1) [Snipped down to get under the character limit]

2) Dissipation is a lower level Summoner Seraph that upgrades to Summon Seraph at level 80.

3) Make Dissipation Rhizomata. Yay homogenization, I guess...! \o/

So there are some way to make side-grades or change Dissipation to where it makes sense in SCH's leveling, if not its end-game. The second proposal is basically (at end-game) equivalent to just deleting it. The other two are not.
All of these ideas sound terrible.

1. No. This just makes us lose a CD without any compensation. All you've done is bake two abilities together. This is made worse by the fact that you are keeping the garbage that is Aetherpact (which is literally nearly worthless) and axing dissipation (which is extremely useful)
2. Once again, you are cutting directly into our resource management and basically giving us nothing in return. The Aetherflow from dissipation is a massive chunk of our instant healing and burst damage. Let's leave it alone.
3. No thanks. If I want to play a simplified scholar, I'd play sage.