Apple’s plan is to eventually not need a SIM card for their new iPhones. Accordingly, the iPhone will begin using an embedded SIM (eSIM) instead of a physical SIM card.
An eSIM is a programmable electronic chip that integrates into telecom devices and allows them to store network-specific information like phone numbers and subscription details more easily than traditional methods of storing user data on removable plastic cards with chips inside them.
Apple would remove the physical SIM tray from its smartphones in order to save space for other components such as larger batteries or increased screen sizes (the latter seems like an unrealistic option).
Without physical SIM card slots would go on sale in 2022. This claim is reasonable because it takes time to develop new technologies and then convinces consumers that they should use them.
One famous historical example of this struggle was when Apple introduced the Macintosh computer with an easy-to-use graphical user interface which competed against DOS, but whose sales were slow until the mid-to-late-1990s when Microsoft developed Windows 95 which became much more popular among users than earlier versions of Windows.
Today, mobile devices are using SSD cards instead of hard disks, memory cards or USB flash drives for storage expansion while laptops are beginning to use SSDs instead of slower, though cheaper HDDs for their main storage.
I predict that eSIM will be more popular than physical SIM cards in the future. However, it may take longer to phase out physical SIM card slots if eSIM is not always as reliable and consistent as a plastic and metal chip.