Prior to the release of ios 11.3 (released somewhere in march 2018 - so very recent!) the only way to have homekit-integration was by using an authentication-chip from Apple...
This was not easy to use and that would mean new LM-hardware with integration of that chip. This would mean buying a new LM...(good for openrb!!!)
See article
https://www.imore.com/how-homekits-softw...tion-works
Now with ios11.3, software authentication is possible and allows homekit integration in existing products through software updates.
I also strongly believe that voicecontrol is something that is absolutely required in a product like LM. I am using siri/homekit for a while (thinka) and it is super to control lights, blinds, fireplace, heating, etc... by (dutch) voice from anywhere in the world. I am also using carplay in my car, just with the push on the button on the steering wheel I can voicecontrol my KNX-system from anywhere in the world while driving: open blinds, open the gate, turn the heating on, etc all by voice...and without opening any app/pushing a button in an app.
What i also see is that the need for a separate visualisation (very time intensive and costly to create!) to control your home-automation is becoming less and less important...the home-app allows for easy control, making of scenes, automation (geofencing works nicely), etc. and it all syncs to all your iphones/ipads.
Next step for me will be the apple homepod speaker: putting just one in your living room means control everything through voice-commands while also controlling your music...
I know that with google home/alexa you can do a lot of the above also but it is not yet everywhere available and not in all the native languages (like dutch in my case) and there is also the question of privacy...I still trust apple more than google/amazon with my data. With apple you have one easy homekit setup that allows control everywhere in the world using an ihone/ipad/watch, using your voice in dutch, siri in your car...all of this functionality in one system is very difficult to achieve with the competitors at the moment...
What I also see is that customers with the money to install a full blown KNX/home automation system in their house most of the time also use iphones/ipads and other apple equipment.
I believe there will be a moment when a customer will require siri/homekit as mandatory for a domotics-installation. So I believe homekit-integration in LM will become mandatory also.
Hopefully we see homekit integration in LM somewhere soon...