How about a series detailing the development and later destruction of the humanoid Cylons from Kobol on the original Earth, or would that be too much like Caprica? Or a series detailing the build up to humanity's exodus from Kobol? Or something Cylon-free, set during the period when the Colonies were developing advanced spacefaring technology and fighting with each other?
I think anything Kobol related would be too far rooted in it's own history to be interesting (unless it were done in a good way, naturally).
It would be like Star Trek doing the story of the Zephram Cochrane inventing the warp drive... oh no wait...