I wish I just had one device. Imagine a phone that unfolds to a laptop, and then can plug in to a keyboard and display and become a reasonable computer/laptop.
Samsung is sort of there with the Fold and Dex, but Apple could really nail it.
Palm Foleo? There were multiple iterations from different companies (among them Motorola). Perhaps Apple could get it right, but then, Apple happily sells you multiple devices.
Samsung is sort of there with the Fold and Dex, but Apple could really nail it.