Juli Clover, writing for MacRumors:

When attempting to install iOS 9 on a device with insufficient space, there’s a popup that offers to temporarily delete some apps in order to make room for the update. Apps that are deleted are then reinstalled and replaced after the operating system update is completed.

This is a fantastic idea. A bit of a hack, made necessary by an OS update size that outgrew the smallest iOS device capacity. But a terrific idea, nonetheless.