If the CPU is disconnected from the device it will not continue to function. Failing gracefully is the best you can do and even that is incredibly hard. Are you going to give the CPU its own battery so it can keep its cache when removed?
BUT, that was for one vertical application which the complete application stack is under my total control - all configurations are sync when in hot standby mode.
Android system which anyone is able to install any type of Apps are completely different stories. The design will be much more complex to handle all the cases - I am not sure if that's even possible.
It is a good science project - not sure about any commercial potential.
http://blog.phonebloks.com/post/101254153023/video-project-a...
I believe this is like an eternal prototype, not meant for mainstream.
Make a fat, ugly device with low battery life and experiment with different concepts.
I assumption is they'll take learnings from Project Ara and apply it to a new, 'production' phone that has like a detachable camera or something.