iOS 8 and resizable iPhones

At WWDC two different things were announced that are inter-related but to me don't quite fit. 

Xcode 6 now includes a resizable iPhone and iPad simulator for testing. This means that instead of testing on a 320x480, 640x960 or 640x1136 sized iPhone or iPad, you can make an iPhone or iPad whatever size you want. 

The other addition was size classes which allows the layout to change based on the size class of the screen rather than the size of the screen. For example, an iPhone has compact width while and iPad has standard width, allowing the programmer to choose specific layout to suit.

These announcements have lead to two theories about what this means for the future of iOS devices:

  1. The iPhone will have a different resolution screen. There are rumours around what physical sizes might be released but this seems to indicate that different resolutions might be offered too.
  2. There could be the ability to run multiple apps on screen at the same time on the iPad.

While both of these seem possible, or even probable, I wonder if we are missing something else. Size classes seem to be a big deal but running multiple apps doesn't really seem like a big deal (for most people).

Is there some other reason that size classes could be coming that no one has thought of yet? I can't think of anything but maybe it will all make sense soon.

Update 2014-09-13: Looks like the new iPhone has been announced. No real surprise there. The resizable iPhone in Xcode still seems like a bit of a mystery to me that hasn't really been explained. New iPads are likely to be announced in October (if last year is anything to go by). Maybe it'll all make sense then. Leading contenders are larger iPad or multiple apps on screen.