Colin’s idea was to keep the shorter side of the iPhones screen the same, i.e. 640 pixels at 1.94 inches. With that in mind how much would the longer side need to increase so the that diagonal measurement was 4 inches. The answer, derived using simple algebraic rearrangement of Pythagorus’s theorem, 1152 pixels and 3.49 inches. That leaves the the diagonal length measuring a little over 3.99 inches, I’m sure Apple PR could round this 4.
An iPhone proportioned this way would be weirdly tall — and Apple is not known for making things that are badly proportioned. This Colin person pulled this out of his ass, and I don’t know why The Verge would bother publishing an article about it.