Nice try Bioware, but I know the state of Southern Thedas better than you do.
First off, it matters if the Hero of Ferelden is alive or not. When the First Warden recalled all wardens, our hero knew that was a bad call and refused, finally splitting off from Weisshaupt after years of mismanagement and taking scores of wardens with them. Their presence and leadership makes all the difference, rallying southern Thedas once more against the blight. If you have only an Orlesian Warden Commander in Amaranthine they’re less inspiring, but as long as you’ve done Awakening they are a boon nonetheless. There is someone to lead the fight against the darkspawn while other focus on the Venatori.
If you 100% completed Awakenings and also Soldier’s Peak, the Ferelden wardens have never been so prepared. They’re organized, they’re outfitted and they’ve been ready for this for years. Also, if you allied with the Architect then you have scores of strange research to give you an edge.
If Merrill completed her Eluvian then she moves south once again and joins the effort. She’s managed to cleanse the blight before and she’s ready to try it again. And her knowledge of the crossroads gives the south an edge on their movement and supply lines. If Hawke’s sibling is a Warden they accompanied her.
If the Inquisitor let Briala have power in any way, the Dales become the leaders in the war against the Venatori, forming a formidable alliance with Ferelden, Orzammar and the Marches, the likes of which have never been seen. And if you completed Jaws of Hakkon then their alliances with the Avvar and Chasind are stronger than ever.
Of course, if the Inquisitor kept the Wardens around after Here Lies the Abyss then their numbers are bolstered. It may cost Wiesshaupt later, but that’s Rooks problem. And if you completed the Descent, then the Inquisitor and Warden had a much better idea of what was coming and spent ten years getting ready.
They will weather this storm.