It's pretty apparent that the purpose of this DLC is to establish canon with regards to Morrigan/DR for DA2. There will probably be only one end result of this DLC, or at most, several "different" endings that are interchangeable as far as carryover to DA2 will be concerned.
The developers essentially had three options regarding carryover of Morrigan's fate to DA2:
1. Ignore the choice regarding Morrigan and leave it out or accept only one outcome as canon, creating a major plot hole.
2. Write two whole games for DA2 at great expense to address each potentially world-changing outcome of the DR choice.
3. Establish some events between DA:O and DA2 that we accept as canon but effectively render the original decision irrelevant.
I realize that the third option is the best compromise, but I can't help but think how the possibly epic consequences of my decision in DA:O will be wrapped up in 7 bucks and a few hours of buggy gameplay.
Ex.:
SPOILER
Take a female GW for example, who has Alistair or Loghain knock up Morrigan for the DR. You're creating not just a demon baby, but one who has claim to the throne of Ferelden. This is a pretty epic premise. But what if the writers whip up a DLC saying how Morrigan is canonically dead because she died in childbirth if you did her DR or got eaten by a bear if you didn't, ultimately having the same effect on DA2 but at the same time, utterly LAME.
Obviously (I hope), Gaider won't do something like that, but even an epic battle with an Old God baby (if you did DR) or (a possibly returned from banishment, depending on your other actions in DA:O) Flemeth (arbitrarily chosen because she has a high dragon form and she lives in southern Ferelden, where the DLC is said to take place) would mean the same thing: no more Old God Baby to deal with in DA2 and a decent bossfight even if you chose not to do the DR.
At the very least, this does lend weight to the Arlathan speculation for DA2 because we now have crossed off the first two items on Arl Foreshadow's grocery list (Orlesian Dictionary > Awakening; Offspring and the Fade > Witch Hunt) and we know that, because this is the last DLC, Forest Fall must apply to DA2.
END SPOILER
For all that I naysay, I still expect to be purchasing Witch Hunt because, while there may be a dissatisfyingly general ending, I want to know what it is. And hey, maybe there isn't. But there's only so much that $7 can buy.