The exact details are still up in the air on this one and it's likely that this will see a couple tests. The goal is to remove the macro requirement, thereby lowering the bar to entry, and also to lower the ceiling as well.
The only thing so far that is definitely happening is that charm will be able to run concurrently with all other pulse spells. This will remove the need for macros.
As for the other part of the change, we're still discussing it and are not entirely sure yet on how exactly to best achieve the goal. Possible options include making charm have a cast time and be uninterruptible, adding a cooldown and similar things.
In general, our goal here for lowering the ceiling would be that high level pets should have some downside (or be straight up impossible) and that there should also be some counter to the CC removal, not an easy counter but some actual counter with coordination.
EDIT: Exact changes below
1) Charm pulses can now run concurrently with other pulse spells, in practice this means minstrels can run speed or ablative or flute mezz while having an active pet without having to spam charm in-between
2) Minstrel charm spells will receive a 6 second cooldown
3) Manually releasing a pulse charmed pet (e. g. via the Release button on the pet window) will now also cancel the charm pulse. This also applies to mentalists.
While working on 3, the way pulse charmed pet releasing works, a bug was found that could sometimes lead to inconsistent behavior of the pet afterwards. Technically the pet release for pulse charmed pets is now only done via expiring the charm effect and no longer via expiring the charm effect as well as also explicitly releasing it, due to some timing issues the latter could sometimes lead to unexpected behavior.