Something I thought about this morning - on YJ, it would appear that The Light partnered with the Reach just so they could convince Mongul to bring Warworld to Earth where The Light could steal it. Ha!
There's been a ton of speculation about exactly this going around.
The Light are being portrayed as actually intelligent and Savage seems to have true visions of empire. My favorite guess about what the 3rd season could have been: a forward time jump to an era in which the Light get everything they want. They're the open leaders of Earth, and Earth has become a power in the galaxy.