None of them would be exactly as they were, or are now. It'd be more like the Artefact system than anything else; you unlock them over the course of levelling to the new level cap, and perhaps for a short while after level cap. It's a WIP concept, but that's the jist of it. As in my original post, it can be expanded upon in future expansions, instead of thrown into the trash like every other system they've come up with.
Using the Retribution Paladin as an example, this new system would see the return of traits such as:
- Divine Tempest: Artefact trait
- Empyrean Power: Azerite trait
- Ashen Hallow: Covenant power
- Truth's Wake: Covenant Soulbind
- Sacred Judgement: Retribution T20 4p bonus
- Wings of Liberty: Retribution T18 4p bonus