Apple planned to introduce solid-state tactile buttons in the iPhone 15 Pro, then in the iPhone 16 Pro, but this never happened. After that, rumors appeared that the project was suspended, but, according to information from a Chinese insider, cited by GSMArena, the company still continues to develop this technology.
The main obstacle to implementing the new buttons has been accidental presses – for example, when the user accidentally touches them – and their sensitivity has not yet met Apple's expectations.
Apple is also improving the tactile feedback and reliability of these buttons to make them as comfortable to use as traditional mechanical ones. It is important to the company that they provide the same user experience across all devices.
The main advantage of tactile buttons is that they can be programmed to perform different actions depending on the force of pressing. They are also free from mechanical wear and can improve the device's protection against moisture.
Apple is not currently tying the development of this technology to specific iPhone models. The company is working on improving it and will only introduce new buttons when they meet its standards. So, you shouldn't expect them in the iPhone 17 series just yet.