[X-Istence]

Hue bulbs currently are stock standard Zigbee compatible light bulbs. You can pay them into ZHA/Z2M without any issues and control them without any Hue hub or app.

If Hue were to suddenly switch to something proprietary their existing bulbs will all continue to function without their app or hub.

[grahamj]

The bulbs are ok but I tried moving my Hue motion sensors over to my main Zigbee network and they were terrible, constantly dropping offline and needing reset.

Luckily Hue is made by Philips who I'm pretty sure aren't going anywhere.

[X-Istence]

I moved my Hue sensors to my primary Zigbee network and left the bulbs on the hub, especially since I have some of the gradient strips that don't work unless they are on the Hue hub, and my motion sensors have been rock solid.