At this point I’m hoping they are looking to implement a lore friendly reason characters can swap abilities on occasion. As much as I hated the idea of just relegating them to a new talent row it would probably be the safest option and allow us to choose a covenant based only on RP factors.
I liked the idea of covenants being a significant character defining choice that included power, but this particular system just doesn’t fit the game as it is today.
If we still played in a classic-like world where you only had one talent build (or duelspec at most) then the covenant system would make more sense and you’d be making one more decision that defines your character. But the game has set the expectation of being able to swap specs at a moment’s notice. Heck, most gear still swaps primary stay based on your spec. The only thing that doesn’t is azerite gear and people hate that mess.
It also just isn’t going to be balanced. I’d personally be fine with something balanced within a few percentage points but they are nowhere close and it’s broken well beyond the range of what a numbers pass could hope to solve.