"He's an unkillable darkspawn with an army of renegade mages and a blighted dragon." Perspective, Alistair, it is important to have it. Even if he has his own army, even if he has the wardens- someone must be realistic as his Advisors are so intent on foolish optimism. Only Cullen seems to share his wary dread of what is to come- only Cullen seems to feel somewhat sheepish for how they conned him into this position.

"I'm fixing this mess of the Wardens and then I am finished." Or dead. Probably dead, but finished none the less. They can find another elf to puppet about Thedas.