We imagine macOS, tvOS and watchOS will get updates too. Rumours about macOS and tvOS are thin on the ground, but macOS seems overdue a Health app, Apple Fitness+, desktop widgets and Catalyst apps that feel like Mac products rather than hurried iPad ports hurled on to a Mac.
Apple Watch is arguably the one to, erm, watch though, given that Apple has in recent years had a habit of doing really interesting things with watchOS. One biggie we know about is someone being able to use an Apple Watch without even touching it (from the new accessibility features), which is pretty awesome.
Other new features will presumably require updated hardware, though, such as taking measurements for glucose, blood pressure and alcohol levels – and it’s vanishingly unlikely new Apple Watch hardware will be revealed at WWDC. There might be hints in the watchOS beta code, however.