Can any recent iPhone benefit from the AirPods instant pairing?
Yes, the iPhone 5 and newer running iOS 10 can be paired with headphones equipped with the W1 chip.
From Apple's website:

Beats Solo3 Wireless is ready to go when you are. They instantly set up – just power on and hold near your iPhone – and then simultaneously connect to your Apple Watch, iPad and Mac*.
*Requires iCloud account and macOS Sierra, iOS 10, or watchOS 3