Are multiple iPhone sizes coming?

Jean-Louis Gassée:

How long before customers look left, look right, see everyone with the same phone or tablet and start itching for something different? My friend Peter Yared contends that the trend has already started in the UK where the “18-25 class” now favors the smorgasbord of Samsung devices as a relief from the iPhone uniform.

I appreciate what Jean-Louis Gassée is after here but the argument doesn't quite stand up.
Apple's strength derives from its focus, iterating on a few core products endlessly. Multiple iPhone sizes don't mesh with that philosophy.

Besides, the iPhone gets a cosmetic refresh almost every year to keep things interesting. If demand gets high enough, Apple could always crank out a few iPod like color variations alongside the requisite white and black.