Note that enterprises, and expert users, can still provision a custom push profile that routes these notifications through their own hosted push server rather than through Apple’s. This is not useful for App Store users, but App Store users are also not likely to know or care about this change.
For chat apps, you use push notifications to alert users and wake up the app, that can do its own downloading through its own protocol. You don't need to use pushes to actually deliver content unless it's relevant to show to the users
If you want to try anyway or you're in one of the rather contrived situations where Apples solution doesn't work, consider an Android device.