The smartphone was invented long before the iPhone. This is 10 years after it went mainstream.
And in ten years that iPhone has not changed much, except that the CPU/GPU rapidly caught up to current standards. The only other dealbreaker toward using it today is 3G support, and that's a 9 year old feature. If the iPhone 3G had the same relative performance to 2008 desktops as the current iPhone has to 2017 desktops, it would probably still be viable.
Maybe 10 years is a bit too high, but we're talking about high end phones here. I'd be surprised if the actual hardware wasn't acceptable 7 years down the line.
And in ten years that iPhone has not changed much, except that the CPU/GPU rapidly caught up to current standards. The only other dealbreaker toward using it today is 3G support, and that's a 9 year old feature. If the iPhone 3G had the same relative performance to 2008 desktops as the current iPhone has to 2017 desktops, it would probably still be viable.
Maybe 10 years is a bit too high, but we're talking about high end phones here. I'd be surprised if the actual hardware wasn't acceptable 7 years down the line.