The idea of having a normal screen on the front but then a second foldable screen inside is a great tradeoff between form and function.
Unfortunately I can’t see Apple releasing this because it harms their tablet sales. Hopefully I’m proven wrong though.
I suspect the real reason they haven't released a foldable yet is that foldables still need to have a soft plastic screen and a crease/bump in the middle, and Apple's design neuroticism would never permit them to ship such a thing.
I really don’t want to leave Apples ecosystem but when my phone is due for renewal later this year, I’d seriously consider switching to Android if it meant getting a foldable screen.
Putting aside the biggest issue which is a creased and more fragile screen, I’m not really convinced it’s a better experience. Having more real estate for movies seems useful, but it’s otherwise difficult to type/hold/tap on such a large screen without a full commitment to tablet usage (which often includes a stand). I’m also not really sure how often I’d use the larger format.
But you can then fold the phone open to get access to that wider screen.
So you get the best of both worlds, a normal phone handset for one handed action. But a larger screen for when you want something that’s a little more “tablet” like.