I'm pretty sure they're sticking with the "Hard Covenant Choice" at the very least through 9.0. They seem quite committed to the idea of it being a decision on par with Race and Class.
There's always going to be an optimal choice, but they're going to tune the numbers so that they're all within a certain range. This is probably ultimately going to mean that you'll get some Class/Covenant combos that have shitty active abilities but really strong Soulbinds and vice versa.
If that doesn't work I'm pretty sure that some time around 9.1 they'll just introduce some new system that allows you to gain access to the abilities and Soulbinds of the other Covenants. I don't see them "solving" the "problem" of Covenants purely through systems if they do decide to make a change. It'll be justified through gameplay and story somehow.
Maybe you'll be able to form "Pacts" with the other Covenants and funnel some of your Renown into them.
Or maybe it'll be something really simple, like the Covenants will band together as the "Umbral Accord" or something and build a new hub Sanctum in the Maw or whatever other new zone is introduced, and in that hub you'll be able to mentor under the other Covenants to learn their abilities and soulbond with their members while still remaining loyal to your chosen Covenant.
That would make sense from a "choice" and "RPG" standpoint while also not devaluing the original Covenant implementation. It would feel like a natural result of the story progressing.