As cool as it sounds, I don’t think blizz would want to introduce a tanking spec to us as that would put us on the same level as druids, which are supposed to be the “versatile” class.
I think its more likely we get an augmentation style support spec, as in vanilla, shamans (and pallys) were the OG support specs. Honestly “enhancement” sounds more like a support spec than a pure DPS spec.
Here’s how I would do it:
Resto - Water-focused and ancestral, Healer
Elemental - Master of All 4 elements, Ranged DPS
Enhancement - New support style using totems and giving imbues, Support DPS
Stormbringer - Storm-focused melee (Uses gameplay of current enh) and Animal Spirits, Melee DPS Hybrid