Back when the iPhone 5 was released, it felt huge compared to the extremely tiny 3.5" display but now of course we've grown accustom to this size. So, then is 5.5" the biggest it's going to get? I honestly believe it's not and that customers will want more in a few years, although I have an idea of how they could fit a bigger display into a pocketable design. 5.5" may very likely be the biggest option for 5-6 years though. 3.5" felt satisfactory for a while, and customers will tire of a minuscule 5.5" eventually too.