Mmm, well I will tell you that the the head unit 2016 and before (nobody has checked the 2017 unit yet) does not have a stock HDMI in interface like the TLX and ILX do. Even then, those two vehicle cannot easily switch to HDMI mirroring without going into the developer settings of the head unit. That means that you will need to add HDMI via a mirroring device like a Naviks or Navtool, which both will mirror the screen via HDMI, but do not carry the audio signal over the HDMI and instead rely on the AUX input of the vehicle for audio. That brings up another issue since we're talking about OS updates... HDMI interfacing works due to the MHL protocol, which is being phased out in favor of DisplayPort over USB-C soon (it's actually already gone on some of the newest phones, especially USB-C devices). And then you would still need BT for the phone call and text interface since that is the only method that carries such data to head units.
Sooo yeah, I've been personally holding off on mirroring and HDMI devices because I have a USB-C phone and also because Google decided that it wants people to use wireless mirroring on its newest phones. In the future, I expect that our head units will need to implement a wifi interface for phone and head unit interaction, but it's just a matter of when. With more and more manufacturers moving to Android based head units, keeping the head units and phones working with each other might become easier (maybe.. depends on if the car manufacturers want to make this a revenue stream option as well).