All right. So I think it's clear as mud that things played out somewhat along these lines:
1. Humans on Kobol. They make Cylons. Cylons rebel. War!
2. They fight for a while, and the humans go off to found the colonies. The Cylons go off to find a home far far far away. Kobol is abandoned.
3. The Cylons, either on their way to Earth, or when they arrive there, evolve into human-form. They don't limit themselves to twelve models; there's a wide variety of skin tones and ethnicities and they emulate the Kobolians as best they can. Essentially, they've become their own "human" colony, with the only difference being that their brains run machine code, not humanware. Some of the original toaster Cylons are still around, chilling -- these were the ones we saw along with the skeletons.
4. Someone nukes the Cylon colony. I think it was survivors from Kobol -- either direct Kobol descendants who never made it to the twelve colonies, or people from very early on in the history of the twelve colonies, and it's just not in recorded history. I don't buy that the human-form Cylons who lived on Earth built their own toasters that then attacked them.
5. Five human-form Cylons manage to download and resurrect after the calamity. Experimental tech? Maybe. Either way, they're emo about what happened so they wipe their memories, and they're lonely so they go off to find the descendants of the humans from Kobol in the colonies. They integrate into society, lay low, and maybe keep resurrecting over several lifetimes. Maybe they brought resurrection tech along with them on the ship that they used to get to the Colonies in the first place.
6. The Colonists make robots as well, which resemble the original Kobol models. It's probably reasonable to assume that someone who had a hand in designing the first batch also has a hand in designing this new batch, since "our" toasters look similar to the 2000-year-old toasters they found on Earth.
7. Just like Kobol went to war with their Cylons, the Colonies go to war with their own. They're not destroyed or abandoned, however -- instead, the Cylons go away somewhere.
--> Now here's the interesting part. If the 13th Tribe Cylons left their original home, Kobol, to found a new home, Earth, and everything is cyclical, then it stands to reason that the Colonial-Cylons also founded a new home. The Colonial-Cylon Homeworld is equivalent to Earth in this cycle.
For all we know, there's millions of Cavils and Dorals and Natalies running around food markets, playing Dylan, whatever.
I kind of feel that the Cylon Homeworld will therefore come up before the show is over. Plus, where else would they go?
Share your thoughts on my devious little ideas.