It exists, but is almost certainly doomed. 2 Unsundered Ascians are still around to continue the Rejoinings and re-mantle lost Sundered Ascians. Hydaelyn in our own timeline was barely strong enough to possess Krile to speak to us, let alone provide the same amount of direct assistance she did in ARR in confrontations with the Ascians. Future WoLs will not have the same advantage we had.
It's a trope in most time travel media that if you time travel back to the future after changing the past, you go to the new timeline's future and stay on the same timeline instead of skipping over whole timelines. I don't see why this would be any different unless the writers want to go out of their way to make some AU Ancients happy.
This is an MMO so we have to deal with the limitations of having to be chained to the original world and always having new threats to face until the service ends.
We're the player character. We're not going to sacrifice ourselves and become unplayable. The writing around Elpis wasn't great and the dance around time travel repercussions was awkward, but it's silly to suggest that there's a better end for the Ascians they could've gotten or that our WoL needs to pull out all the stops to save them. It's a trolley problem because either their world exists or our world exists. In the timeline that our world exists, theirs cannot. One world needs to end in order for the other to continue. Opening up room for both to exist simultaneously in separate unique timelines is meaningless because in the timeline that will always be playable that we have been in for a decade, the Ancients have to die in order for it to exist so there will always be a failed world of dead Ancients that got Sundered no matter what you do.
They could have made a throwaway line that would affect a whole other timeline of Ancients, but it still won't change the fact that in our timeline they die and I'd rather the story address the ones who have direct involvement with our timeline rather than a separate one that won't matter. Ultimately the Ancients are backstory for the world and an explanation for the Ascians long after the Ascians were originally written, they're not the main event.