For me the old phone would be pretty painful. It's an iPhone 4 with 32 GB storage (max), 960×640 display, 5 megapixel camera, and no LTE. It's got a 32-bit processor with half as many cores as my current phone, running at less than half the clock speed.
Not all technologies improve at the same rate, or at a steady rate over time. But the optimal replacement interval of goods on average seems to be decreasing.
