Preview at WWDC likely in June, followed by September launch.
Apple Releases Second Beta of iOS 11.2 for Developers
Registered developers can download the iOS 11.2 beta from Apple's Developer Center or over-the-air once the proper configuration profile has been installed from the Developer Center. Apple already released beta 2 for the iPhone X, but this new beta will be available for all devices.
iOS 11.2 addresses an animation bug in the Calculator app that caused some numbers and symbols to be ignored when entered in rapid succession. The update removes the animations from the calculator app so calculations can be done quickly with no need to pause between entering numbers to obtain the correct result.
In addition to the Calculator bug, iOS 11.2 introduces a new Now Playing option for controlling content on the Apple TV in Control Center, redesigned camera emoji, and a new loading animation for Live Photos effects, and it appears to introduce the TV app for Sweden and Norway.
Several other promised iOS 11 features have not yet shown up in the current beta but could be added ahead of the update's release, including AirPlay 2, peer-to-peer Apple Pay, and iCloud support for iMessages.
Update: According to Apple's release notes, iOS 11.2 beta 2 adds a feature that lets developers offer new customers discounted introductory pricing for auto-renewable subscriptions on the App Store.