Use it as your webcam. Best quality camera you'll find, continuity camera feature on macos are great like desk view.

Slap in a pair of external microphones into the lightning port and you have a pretty good field recorder with a touch screen and rechargeable battery.

Or load AUM, plug it into an audio interface with a camera connector and you have a digital mixer.

Or load Garage Band and you have a Daw in your pocket.

Capture realtime facial expressions on UE.

Just for fun. Kinda whats I am doing these days

iOS is to iPhones what Windows is to PCs

Put another OS on it and use it for many more years

(though I don't know the status of jailbreak or alternate OSes for iPhones as my last one was a 3G and Cydia was a thriving ecosystem then)

see nasreborn.com - just read it this morning

Setup OpenBubbles! You can iMessage from your Android.