The iPad 5 could feature a brand new accessory if a recent patent filing from Apple comes to fruition. The company has designed an inductive charging Smart Cover that would wirelessly transfer power to and from a future iPad. The Smart Cover itself would operate much like today's models.
The difference is that the charging Smart Cover would contain its own battery and the components needed for inductive charging. The iPad itself would also feature wireless charging hardware, which would operate when the cover is closed or used as a stand.
Either the Smart Cover battery could be charged via Lightning cable on its own, or the cover could charge itself using induction from a plugged in iPad. Once the iPad is unplugged, the Smart Cover would be ready to provide backup power and top off the iPad battery whenever possible.
The inductive charging Smart Cover could even be used to wirelessly charge additional devices, such as a future iPhone or iPod touch. As Patently Apple notes, the entire setup including the iPad 5 and Smart Cover could even be wirelessly charged by placing the device next to a future iMac compatible with the technology.
Assuming the device is synced over Wi-Fi and iCloud, it's possible that using a Lightning cable will become more of a novelty than an everyday necessity.