Analyst Ming-Chi Kuo can't stop talking about the iPhone these days. After detailing new iPhone 13 features such as a smaller notch and larger battery, and predicting a 2022 launch for the 5G iPhone SE, the well-connected Apple observer is now turning his attention to the iPhone Flip.

The iPhone Flip is the rumored foldable phone that everyone assumes Apple is working on, but no one even knows when it will appear. Kuo throws in his two cents on a foldable iPhone in a research note found by 9to5Mac, and if he's right, we'll be waiting quite a bit.

Kuo doesn't see a foldable iPhone appearing before 2023. And even then, it is not certain that the foldable will ship. In his note, Kuo said that if Apple has any hope of offering such a phone in two years, it must "solve the key technology for foldable mobile devices" and move forward with bringing a 7.5" to 8" foldable device into mass production.

Kuo's prediction is not out of line with what others are saying about the iPhone Flip; Bloomberg reported in January that Apple was testing a prototype of the foldable phone, but had no specific plans for shipping the device. Digitimes is more aggressive, reporting that Apple could have a foldable ready by 2022.

Apple is reportedly looking at two possible iPhone Flip designs. A phone that opens to reveal a tablet-sized screen, like Samsung's Galaxy Z Fold device, or a clamshell-style phone with a screen that flips open. If Kuo's timeline is accurate, it may be a while before we know which option Apple will choose - if the iPhone Flip appears at all.

Kuo reports that 2023 could be a big year for the iPhone. In addition to the foldable iPhone, he suggests that 2023 could see a truly full-screen iPhone with neither a notch nor a notch for the front-facing camera. Kuo expects the iPhone 13's notch to shrink this year, while the 2022 model will have a punch-hole-like cutout in the display to accommodate the front camera.