From what I've read, they are going to be a multi-class only class. So, instead of multiclassing into something else, you can acquire a spellscar and then use it to swap out some powers for your normal ones. Seemed like a decent way to do it. And probably something how they'll do dragonmarks, I'd think...which is unfortunately. haven't seperate mechanics would be a good thing, imo, rather than "These are the spellscars for this world".
I disagree; I love the multiclass-only dragonmark idea and I hope the mechanics get used over and over. Besides, weren't the Dragonmark PrCs the equivalent of this in 3e?