As much as I'd love Jack White, I agree he's also likely just too big of a name. But it's jut my gut. And I would LOVE if GCJr were an annual tradition - he stole Saturday last year, should have closed it out.
I also had wondered about Sylvan Esso, Father John Misty, and Rateliff. I would LOVE to see Leon Bridges and Alabama Shakes, but feel like they're also too big of names at this point. LOVE Anderson .Paak, but not sure if the hip hop thing would fly as a main act at Hinterland? I'd dig it!
Some bands with stuff coming out this year that I would not be surprised if we saw at either Hinterland or 80/35 (esp since some have already been to Iowa):
First Aid Kit
The Shins
Bahamas (I love their new single)
Franz Ferdinand
Belle & Sebastian
Moby
Titus Andronicus (maybe more 80/35 than Hinterland?)
Fratellis
The 1975
My Morning Jacket
Gorillaz looks to have something coming out this year - they'd be amazing, but probably too big?