The Cylons WERE machines, and they "evolved" into bio-engineered beings. As far as who the humans are and what waits for them on Earth, we can't really say for sure, but it is looking something like that. There is something very Xenogears-ish about it, with a bit of Blade Runner thrown in. I haven't seen Gall Force in probably 17 years, but if I recall correctly, that may be about right.
I get the feeling thousands of years down the line, the Cylons will have lost all sense of themselves as anything but human, and to them, in their stories and history, Galactica will be the 13th tribe heading off into space.