There's a logical evolution between the heavy computers of the past and those fancy equipment called smartphones. It's a matter of functionality, and the demand for it. This is the point where foldable screens come into play, because they provide interesting possibilities.
The technology development for hardware like this doesn't look easy as a screen needs to be seamless and have enough rigidity for being watched nicely. If the electricity storage goes different (better) and allows integration in those flexible screens, it would be possible to carry objects like pens but with a considerably large screen. This looks rather ideal to the advent of new technology for sound reproduction as well.
Rumors here or there about the new generation of portable devices. Today it's possible to see people trying semi-rigid screens for wearable options, and it's true that the arm allows a nice space to be used with any screen that fits. A smartphone and smartwatch mixed together? Something like a pen attached to your arm, touching a button and voila! A rigid screen that appears like an roll-up curtain, so you have a nice screen to interact with, allowing a touching screen. Difficult but perhaps not impossible...
Flexible screens are a reality now, so sooner or later someone would try with insistence seamless options with foldability in mind.