I see lots of "alternative steam machines" going around, but none of them have HDMI CeC, which is the killer feature of the steam machine for me.

Hooking up a small form factor to a TV is simple.

Having it wake from sleep with a wireless computer, which in turns turn on the TV and switch to the correct HDMI input just like a console is the real value proposition to me, and none of those really offer it, as off the shelf GPU don't support CeC.