The iPhone needs to get thinner to allow for a foldable phone that doubles the screen size but still fits in your pocket. Nintendo had the right general idea when they came out with their foldable Nintendo DS. They did the best they could with the technology they had at the time but things have progressed a lot since 2004.
6” is good but it’s still a large phone screen. The problem is that people love the 7.9-9.7” screens on their iPads much more. Viewing the mobile version of most websites sucks when compared to reading the full version on an iPad. Also, being able to peruse magazines, comics, and movies on an iPad Mini is still way better than even a 6s Plus.
And now with the iPad moving upmarket in the form of the 12.9” iPad Pro many people will have to make a choice. Do they buy a more portable iPad Mini or iPad Air 2 or go with the iPad Pro that allows for using apps side by side. I’d say get both but not everyone will have that option. It’s a tough choice that could be negated if Apple was to make foldable iPhones that had 8” screens. There would no longer be a need for an “intermediate” iPad. At 8” your iPhone can become a primary consumption device and your iPad Pro can be your primary multi-tasking device.
And for those who thought that the iPhone 6 was already too large and refuse to buy anything larger than a 5s, can you imagine how happy they’d be to get a 6” screen in the same package size? So come on Apple! Make that iPhone slimmer and give us foldable screens. It seems to be the not-so-obvious direction that phones need to go.