Although there are four models, all different from each other, especially in the diagonal and in some technical characteristics, all models’ form factor could benefit from a significant retouching compared to the current range. The initial rumors have always aimed at a total renewal, which would lead the next iPhone to have a different shape from the current one, with a more squared chassis, similar to the iPhone 4 and, probably, to the iPad Pro.
This path, along with other reports precedents according to which Face ID and Touch ID will be included in the iPhone 2021 screen, would suggest an iPhone 2020 with always present front notch, even if more reduced. This would allow you to increase the screen size without affecting the physical size of the phone.
The new design using steel on the edges would force Apple to produce a series of grooves to reduce the impact of metal shielding on radio transmissions. This is why the use of fiberglass or sapphire glass is assumed to protect the tracks.