HomeKit Support

Sonos has not announced any HomeKit support. So knowing knows untibthey do if ever.

That would be awsome. For instance ability to play a song when getting home or stop playing music when leaving.

And I that with Smartthings now

Yonomi can do that now, too.

Yonomi is nice but they cant turn of music when you leave.
As they state "We currently cannot reliably send events to local devices (Sonos and WeMo) when you depart, as you will have most likely disconnected from your home network before the leave event occurs."
But HomeKit lets you use an iPad or AppleTV as a homehub and lets your phone report to it when you leave.

My Smartthings reports when my iPhone comes or goes and can turn on or off Sonos as well and chose what to play. Also can announc arrivals etc via Sonos.

Well Smartthings seems nice but you have to buy hardware and use a third party app. That is fine but if you already have a couple of Apple products (example iPhone and iPas) it could be done without buying new hardware and yet another third party automation app if HomeKit were to be supported.
As an example with Phillips Hue, the integrated Home app works much better with Siri then the Hue app and also works across your other Apple devices without having to install anything new. You also get direct access to your HomeKit devices through the command center by just swiping up on your phone.