A few things seem certain at this event. It's safe to presume Apple will introduce the iPhone 11 family with more rear cameras (two on the XR replacement, three on the XS/XS Max sequels), improved Face ID and maybe, possibly two-directional wireless charging. You'll also likely hear about release dates for iOS 13, iPadOS, watchOS 6, tvOS 13 and macOS Catalina.
Other items are up in the air, though. There might be an Apple Watch Series 5, but it's also possible that the company could simply tweak Series 4 with ceramic and titanium options. There's also a rumored Tile-like item tracker and the (less likely) possibility of noise-cancelling AirPods and a cheaper HomePod. Apple could introduce new iPads and a 16-inch MacBook Pro, but it could just as easily save those for a follow-up event in October. And of course, people are still waiting on release dates for the new Mac Pro as well as Apple TV+ and Apple Arcade. In other words, this could either be a by-the-numbers event or packed to the gills with surprises -- you'll just have to tune in to find out.