No. Both because an Exalted March wouldn't help it, and because the Dales are on the opposite end of Thedas from the qunari.
An Exalted Marches were called to help and in alliance with the hated Tevinters, so what's your basis of claiming an alliance with elves could not occur?
And the Dales are not on the opposite end of Thedas from the Qunari in a strategic sense. The Dales are right by a sea lane, and the Qunari are an established major naval power. They can sail there.
Perhaps you could choose to side with the qunari. They weren't planning to stay, and might allow the elves and those sympathetic to them to hold the city in exchange for retrieving the book. Depending on the situation and how corrupt the Andrastian leadership might be (if the plot shifted around to accommodate this), you could still almost certainly have Aveline remain on your side, and thus the guard might not throw all their support behind the templars. As for the Circle... I think they could be convinced to see the merits of the alliance.
And then what? The Qunari take their book and try to stay in the city, which results in an Exalted March that annihilates the opposition and destroys the mages, or the Qunari take their book and leave the city. In which case the mages either leave the city with the Qunari, who will be free to enforce the Qun on them as the Qun demands, or they do NOT leave the city with the Qunari- in which case the collaborators are left to the tender mercies of people who can rightfully call them traitors.
No matter what happens, the mages would lose. They would delegitimize themselves and their cause, and for a fecklesss, irresponsible defeat for any intent of mage empowerment.
Besides, Aveline's never been a stickler about corruption- she's one of the most corrupt authority figures we know of in the story, albeit a very sympathetically handled one in a game very, very soft on corruption. She's always been concerned more about the wellfare of the city- you'll need a great deal more to justify her siding with a hostile invasion force. (Assuming we're talking about, well, Aveline, rather than 'some other personality to suit me who looks and sounds the same.')