(Asked about whether “both Vigil’s Keep and Amaranthine were saved” is an option is the Dragon Age Keep)
You can. If you build up Vigil to max you can save the city & it won’t fall.
It’s not something foundation shaking, but one of the options in the Dragon Age Keep is to save both the City of Amaranthine and Vigil’s Keep in Dragon Age Awakening. The epilogue for Awakening had a lot of bugs, but the Keep devs are referring to the writers when it comes to confusing or contradicting lore and the conflict of the City or Keep was one of them.
So yes, Amaranthine can be saved with the help of the Wardens and if upgraded Vigil will stand through the attack. How this effects Inquisition, if at all, will be interesting to see.