There's no shortage of predictions and leaks around what Apple will announce at WWDC tomorrow. I'm going to add one more.
Since this is the developers conference and iPad seems to be getting a renewed focus I'm going to predict/hope for XCode on iOS. I don't expect something that's as powerful as the Mac version but I'm thinking a Swift code editor and potentially the return of Interface Builder. Being able to lay UI elements out on an actual iPhone and iPad screen would be fantastic. Checkout your code onto iPad, do some changes and submit it to your CI workflow for building etc would be very powerful.