Follow the headline link and scroll down about halfway to that animated GIF showing a piece of glass, folded over and being repeatedly squished and released. To me, that is the future of foldables.
That is super-thin glass, 75µm thin. That’s ballpark the thickness of a human hair. And that curve gets down to a 5mm radius.
Fold it over and over again, and there’s no crease. Plastics crease when folded, glass like this doesn’t.
My instinct is that Apple will hold out for glass like this if and when they ever release any sort of foldable iPhone. Details are all in the article.