At the Apple Platforms State of the Union they appear to have confirmed that an iPhone fold is coming. "Now instead of designing for specific devices and orientations, you're designing for a dynamic range of sizes and aspect ratios."
They now offer support for resizable iOS apps and iPhone mirroring in the beta dev software and apparently the full size matches the leaks of the form factor of the new folding iPhone when open.
I'm about due for a new phone so I think I'll get one when available.
Will Garmin optimize Pilot to take advantage of the new form factor? I'd love to skip having a separate iPad mini to carry around.