With regard to the rumoured 960 x 1704 resolution, this could potentially make sense on the 4.7 inch model running in a 3X mode. The user interface would be larger than current devices though, approaching what you get on the full-sized iPad. That might be a little unsettling for users moving from the iPhone 5 to iPhone 6.
For a 5.5 inch iPhone it is difficult to see 960 x 1704 working. The interface would be too small at 2X but too big at 3X.
that's the problem with apple and their iOS. In android, you can change DPI settings for any app and/or the entire UI.
iOS is just like OS X, stuck in the past!