Apple abandons clamshell iPhone plans
Back to the drawing board.
Recently, it was rumored that Apple is scrapping their plans to build a clamshell foldable iPhone, mainly because they felt that it did not serve a new use case. While this is sad for some, it sounds to be good reasoning.

The only major use case that can be found with a clamshell is a smaller size. It is much easier to carry around a smaller phone that still has the same screen size that people need and expect. This is a less proven market for Apple, since the iPhone mini line was not successful for them, and it may have tainted their view. The book style fold also allows for more new functionality in the form of more screen real estate, while the clamshell foldable would improve on other design decisions like size (no new functions would be added, just improved).
This, however, may be a temporary position for Apple. Once they release the book style fold, if it sells well enough, then they may decide to revisit the clamshell idea once a related market is proven. It may just take some time for the folding iPhone market (which has obviously never been broken into by Apple) as a whole to catch up to the rest of the folding phone market.
The upcoming folding iPhones look to be extremely promising, even if a clamshell foldable doesn't arrive soon. We will have to wait and see what Apple does soon.