Apple will never make a foldable iPhone because it serves no purpose and meets no real market demand. Let go of it, it has the potential of a curved screen.
The iPhone WILL have an always-on display, because your Apple Watch already has it.
The iPhone will have a "notch-less" display because the notch is already obsolete.
You will start/enter your car/house via an "always-looking" proximity NFC signal from your iPhone, no touching the phone required.
The iPhone will have split screen multi-tasking, because your iPad already has it.
The iPhone will use Apple Pencil, because your iPad already has it.
The iPhone camera will have night vision.
The iPhone will only accept a virtual sim card.
The iPhone will accept a "cellular-comparable" signal from upper-atmosphere satellites, compliments of Space X.
Your cellular carrier will adapt or go bankrupt.
Your iPhone will NOT display 3D images WITHOUT glasses because the market has no demand for it and Apple will insist you buy Apple Glass, at least thru 2025.
Your iPhone will come with new innovative AR VR solutions per the impending tsunami of the wearable market.
IF, market pressure persists, "one-device-continuity" will become a competing feature. We're practically there already with cloud-based accounts, and we already plug our iPhones into our cars for CarPlay (this is actual, real continuity), now we just need to hit the next step where your iPhone can truly replace your MacBook Air and your Apple TV. Apple will struggle to prevent this as they want you to buy more and more devices, but their competitors may force the market full on into this compromise, maybe... as the market forced phablet displays. Another likely argument for continuity is that as hardware becomes less relevant and more standardized, services are the future.