For all intents and purposes, the Ascians are already done for. Sure there are still a few sundered hangers-on, but basically the "before anything else" has already come and gone. Additionally, Hydaelyn herself is a Primal that destroyed the planet, so...
Even if we want to say that "the JRPG party must destroy the god that was seemingly on their side throughout the story" has turned into a cliché, the opposite is also still a cliché.
She was formatted with the ability to sunder things in that extremely specific way, not to mention the ability to set up a dimensional barrier between the worlds preventing them from rejoining. I don't believe for a moment that it was simply an accident, it was by design and the original sundered world was the state of being Venat planned for.We have no information about her intentions at this point. It could be deliberate or it could be a horrendous accident that happened when she was trying to sunder Zodiark alone but he was too intertwined with the world itself.
As I said, Hydaelyn staying in that position is already a cliché of it's own. And frankly, one which doesn't address all the issues with her that have been building in the story for years. At this point going the route of "she was just misunderstood and actually is unambiguously good and helps you out to the very end" would simply be subverting a subversion for the sake of being meta-subversive. It simply reverts us to the state of play we had way back in 2.0. Again, I fail to see what this would actually add to the narrative, not to mention the story of Endwalker specifically.
Are we really supposed to believe that Endwalker will just be Stormblood 2.0 with few, if any, twists and moral dilemmas along the way? We just go to the moon to kill Zodiark, and chase down Zenos and Fandanny before killing the former with Hydaelyn's blessing? That at the end of the Hydaelyn/Zodiark saga that's spanned five expansions we just end up viewing both of them practically the same way we did at the end of ARR?