Every time I see the rumors of a new iPhone changing the aspect ratio, I just like to think WHY?! Why is this even considered a even viable idea of truth? I know a rumor is a rumor, but we know that Apple makes it's money with minimal changes and excellent customer products and support.
Would they even risk introducing fragmentation into their app store? HELL NO.
Best case scenario is they actually make the phone bigger and maintain the aspect ratio. I wouldn't be too surprised if they keep the resolution, and tweak the ppi to still qualify as retina.
Once again, Apple makes money by using same/similar parts to drive costs down. You think they would change the home button? After years of products, I point towards NO. Even iOS has kept it's consistency so the average consumer can easily move between upgrades.
You want a bigger screen? That's what the iPad is for. Apple knows this.