> We will no longer distribute source code for the entirety of the Solaris operating system in real-time
In the case of Open Solaris, the code never came out from that point onwards. For Android, the likely end goal is to do the bare minimum of distributing only copyleft code that they don't own copyright to. Until those get replaced with a closed alternative.
I'm trying to think of a mobile OS feature addition that has made me say "I need to upgrade my phone" and it just hasn't happened recently. It's more like, damn it, the dastardly thing stopped receiving security updates and now I have to replace it for no good reason.
Isn't Android done yet? What further development is required that couldn't be done by the community?
If they were to stop, the demand for someone to do it would still be there, and that demand wouldn't be getting met anymore, which creates the incentive for others to do it.
Meanwhile the point is that most of "it" doesn't actually need to be done anyway. You don't need to do everything Google is currently doing. Adding support for new hardware is important, but that has an obvious source of someone to do it because the hardware vendors want their new hardware to be widely supported so they can sell more of it. So all you really need is security updates, and a community can handle that as evidenced by the many instances of it actually happening for other code.
What stops the thing that makes Debian work from making this work?
You're right, if Google steps away from Android completely then there would be incentive for others to do it, another megacorp will step in. Maybe Facebook or Microsoft or Samsung.