I literally just got that trilogy today and finished the first book (Where Alistair stabs her, killing her)
...Well, Flemeth got stabbed, she reincarnated. Morrigan got stabbed, she survived. Yavana got stabbed... who knows?
I mean, earlier in the book she DID pull Claudio's spirit out of the fade and force it back in his body... Who is to say she couldn't do the same for herself? She was also resurrecting dragons soo... "Death" doesn't really seem like a barrier to her. A setback, judging by her expression upon being stabbed... But maybe she isn't dead. If they brought her back, I could get behind that. She was extremely interesting, and I feel like she was killed off WAAY too fast.
I agree that she should has a plan to come back and I have some facts to support it
1- She earned the nickname of "The Beast of the Tellari Swamp" she has killed many dudes to protect the grove she should consider that one day they could surprise her and hurt her or even kill her, she didn't seemed so stupid or so proud to believe that it won't happen.
2-The Dragons don't want to hurt Alistair because they need his blood to awaken their comrades, but if they don't have someone to perform the ritual Alistair would be useless and nothing could stop the Queen of Dragons to squash the little selfish bastard that condemned her brethren.
And personally I think that her dead was unfair, she saved Alistair twice and for me she was being honest with him, the kind of evil witch that he claimed that she was would rather threat with kill his friends or fool him to have sex and earn a child with Calenhad's blood.