I can see them dropping support for 3.5 and 4 inch phones.
Which would effectively kill the excellent Display Zoom feature that lets us use the 4" layout scaled up to a 4.7" screen. I can't tell you how important that is for those of us with vision difficulties, but it only works as long as the 4" layout is supported and app makers care enough to test it when zoomed. Apple's own Podcast app doesn't scale right, making it very difficult to delete older podcasts. I'm sure more and more apps won't effectively support Display Zoom, and it will eventually be pulled. Then we're back to terrible text scaling or zoom-and-pan options.