So, in terms of gameplay this all sounds pretty good. It sounds a lot like Mass Effect 3, but it sounds pretty good.
My concern is with this "Corruption"; I'm realizing more and more that Bioware has a bad habit of making the least interesting aspects of their plots the main focus of their stories.
DA: II's problems didn't stem from it's ambition, it had lots of interesting concepts, they were just poorly executed. One of the best things about DA: II was that it wasn't about the end of the world.
"It's the end of the world!" is overused because writers seem to think it's a convenient way to structure a plot, but they too often ignore it's short comings.
"OMG Its the end of teh world!" is convenient because it's flexible, and it's flexible because it's empty; there is literally no sane person who wouldn't be behind such a thing. The plot has no meaning and no nuance because there's no conflict beyond a struggle for survival. The fact that someone is willing to fight for their life tells us nothing about them because it's something anybody would do, the fact that a group of people would organize to fight their own extinction is a meaningless message because it's something anybody would do.
"Someone or something is causing it" doesn't make the story sound more interesting it makes it sound less interesting. Wouldn't it be more profound and evocative if instead of some comfortable, easily stereotyped, unearthly abomination causing all the problems it was just a matter of human imperfection?
While ambition was in no short supply for DA: II, structural discipline was sorely lacking; the game had two major plot lines, neither of which got the attention they needed, and introducing more extraneous bullshit, no matter how familiar Bioware is with it, will only make things worse. The pieces for a compelling story are starring you right in the face, Bioware, stop working so hard to ignore them.