Well, they announce the features of iOS 11 so considering we are still on iOS 11 they still have time. I love that they announce features of iOS 11 and actually deliver during the iOS 11 period. which is now until iOS 12 is out. so there is still time.
Do you prefer only announce features that will be in iOS 11.0.0 at the WWDC then make smaller announcements before the Dev beta is released as features become available? that would be kind of cool actually. make it interesting and on peoples toes