Do you have an iPad? Do you sometimes choose to use iPad for something instead of using your iPhone? Assuming so, why do you do that? Why not use the phone-size screen for EVERYTHING?
Anyone who can rationalize owning BOTH iPhone and iPad should be able to easily see a benefit of getting the best of both in ONE device. Doing better-on-phone things? Use a phone-sized screen. Want more screen RE to do better-on-iPad things? Dynamically expand the phone's screen to have your tablet right there too... in that ONE product that is always with you.
Whether that's folding or rolling or goggles or holograms, I find it incredibly easy to "use case" it. For the short time that I had both a phone and tablet, I found myself using the bigger tablet screen almost all of the time. Just about EVERY app benefits from more screen RE. So obvlously the solution is to have both. What if Apple delivers a way to have both in ONE device?
As in all things, "we" only seem to see no use for something while Apple doesn't offer it. As soon as they roll out
their version of it, "use cases" will suddenly be abundant... and that 1% that is not the "99% who don't need..." will magically become an enormous group of buyers... most of ourselves among them.