Mark de Vries said:
A large Breen fleet may have taken out Earth, but the Dominion would've been unable to hold the line against the Allies.
Why not? the Federation fleets would be struggling to form a new chain of command without Starfleet orders and the Alliance would be fighting a war on two fronts, the Dominion would attack on the Cardassian end of Federation Space and the Breen would launch attacks on the Earth end of Federation space, plus the Alliance would have absolutely no way of defending against the energy dampening weapon since it was a fluke that that Klingon BOP was able to defend against it and it still took the Federation and Romulans a long time to copy the Klingon BOPs ability.
On another point even without taking out Earth when the Breen crippled the Alliance fleet in the second battle of Chintoka they shouldn't have stopped there, they should have immediately pushed forward and systematically crippled all remaining fleets.