What if my iPhone doesn't support iOS 16?

I saw this when IOS 16 was released recently, that a few IPhone device generation are not supported and won't get the upgrade such as

• iPhone 7 Plus
• iPhone 7
• iPhone 6s
• iPhone 6s Plus
• iPhone SE (2016)

what’s the impact will it bring to the phone? is this will affect the current apps or the any interest apps unable to be downloaded through the apple store? or the phones are no longer practical to be use when this thing happen?

Thank you

[Re-Titled by Moderator]