Doing away with the classes would be the most ideal opportunity for the dev team to 'divorce' the two jobs. As a matter of fact, they would accomplish it through pure happenstance if they did that. I know it's in their agenda, so I think your wish will be granted eventually.

As for what would happen to SCH? Knowing SE, their ACN kit would be replaced with another that is different but familiar. Either they or SMN would get new casting animations. Spell cost and potencies very likely to be tweaked. Fairy buffing abilities might be added. Either SMN or SCH would lose aetherflow, which will totally change the way the job is played. The possibilities are quite vast.

From this, we can spend it on 1-2 abilities of the appropriate kind. Say you filled up the Black side, well, then you could spend it all on a single target nuke or aoe dot. Fill up the White and you can spend it a heal nuke or aoe regen. This could even be on long cd's, or the bar could take awhile to fill up, but either way, you are rewarded for being efficient with your time and most definitely defining a style of healing for us.
So divorce SCH from SMN, and remarry with RDM?

Another possible addition that us SCHs have been dying for is fairy glamours. While the ACN class doesn't need to go away for this to happen, I have a feeling that this addition will only come after it does.