Yes, Flocker will remain open-source and my hope is that the community continues to improve it. Fli too, btw, for creating and managing ZFS snapshots https://github.com/ClusterHQ/fli
Maybe donation of the code to an FOSS foundation, like maybe Apache, might be a way of ensuring the community continues. Or, at least, gives it the fighting chance to do so...
I raised that question during the final company meeting yesterday. The ownership of the code is in limbo until the investors decide what to do with it at least a few months from now.