This would be a feature suggestion, especially where you have responsive articles in collections that span across Phone and Tablet top level nav.
ie: same collection has two layouts applied - one for tablet, one for phone.
Dream scenario would be a layout for iOS phones, tablets, Android phones, tablets.
Not too much of an ask, is it?
I had posted this same request a few days ago. Neil indicated that it's a feature they intend to deploy Q1 2016!
Multiple, Device based, Grid and Card Layouts per collection?
This would be really good. Hope this will find its way to the right desk.