It would make sense to have two main types of sorcerous origin: Heritage and Possessed. The first would be all the 'blood of the' types and natural talents, and would have full control over what happens when spending willpower. They'd suit players who wanted a traditional style sorcerer.
The second type, Possessed, would be sorcerers as they've been defined here: with a second soul, struggling with an internal magical entity. They'd have uncontrolled manifestations after spending enough willpower. Of course, there'd have to be a balancing mechanic, such as a bit more willpower for the heritage sorcerers to make up for the lack of manifestations.
Furthermore, I believe WotC are just gonna have to roll the sleeves up and produce a spellpoint wizard, probably via an arcane tradition. Doing so will give them a great deal of goodwill if they get it right.