I believe we will find out that they are all types of Cylons. By the time they get to earth; the cylons will have already blown each other up and galactica will have there own civil war and thus all get killed. In the end they will find Earth but all be gone and it would us the viewer looking at the planet from above.
And if it not that than Boltar is number twelve. It makes no sense for Mr Gaeta to be a cylon. He has been just a sub character and not a lead role-playing character. It all has to make sense and so far from the very beginning the whole series has come together with many woven intricacies. Also a movie therefore would never be in the future. And us fans would all love that knowing that know one could come along in the future and kill it with a remake. This whole series has been great. I look forward to the new episodes and enjoy watching every episode again and again.
I wear my shirt proudly.
"New Caprica Resistance Movement And Pyramid Team"
Frak all Cylons