If you search the forum, you'll see there are a few other threads where the planned, future mobile app has been discussed. However, it might not be what you're expecting: the goal is for it to be used for presence, notifications, and access to dashboards. (As you know, the ST app is intended for device/automation setup and, apparently, device control, though the popularity of solutions like ActionTiles suggests it doesn't do a certain one of those very well.)
Can I ask what your use for the mobile app is? Device/automation setup, as you know, is done via the hub's LAN-accessible web UI--pretty much combining everything you could do via the ST app and IDE into one, except device control is a bit awkward in that it just exposes methods from the device's driver. (Once you get your system set up the way you want it to be, the web UI should ideally be something you need to visit rarely--to, say, set up a new device or troubleshoot an existing one, like to see events history or when it last checked in.) Their goal for device control is to steer people towards Hubitat Dashboard. You can already access either from a mobile device (with the dashboard obviously giving you a much better interface, albeit one you need to set up yourself), and you can pin an icon for either to your home screen if that makes it feel better/more like an app to you. 
Finally, if you're looking for presence or notifications, you can do those already, albeit with third-party tools (Life360 or webCoRE presence if that's working again, for example; and Pushover or the community Hubitat-to-ST notification pusher app/driver for notifications, besides SMS that is built-in if you don't expect to send many).
