Building an image is always possible, that's for sure
Not really, most of the BSP's need modifications to make them compile in Zeus.
Was it indicated that the layer could also be maintained by other users?
This is not uninteresting and would be new.
Then some layers would definitely be added and you would have more to do with the e2.
It is something we might want to consider, (end)users should not be punished because the manufacturer of their STB can't or won't maintain it anymore.
Obviously, there still won't be any manufacturer support for drivers and other manufacturer supplied files (USB devices, HbbTV binaries, etc), so like other EoL images we build, they would come with a limited guarantee...