Preview at WWDC likely in June, followed by September launch.
Apple Seeds Third iOS 8.3 Beta to Developers
The beta, build 12F5047f, is available as an over-the-air download and through the iOS Developer Center. Apple has also released Xcode 6.3 beta 3.
Though iOS 8.2 introduced Apple Watch support, it brought only minor bug fixes and security updates to the operating system. iOS 8.3 brings more consumer-facing updates, like a new emoji picker and all new diversified emoji and skin tone modifiers. It also introduces new country flag emoji and updated emoji icons to represent the iPhone, iMac, and Apple Watch.
Along with those emoji changes, iOS 8.3 brings wireless CarPlay connectivity, support for Google 2-step verification, Apple Pay for the China UnionPay network, and several new Siri languages.
What's new in iOS 8.3 beta 3:
Messages - There's an option in the Messages portion of the Settings app to enable "Conversation List Filtering." With this turned on, messages received from people who are not in your contact list will be filtered into a separate list.
Apple Watch app - Since iOS 8.2 has been released, iOS 8.3 has been updated to add the Apple Watch app to the iPhone's home screen.