Whether or not source code is released is entirely at the discretion of the copyright holder - I'm not sure who that is, but I can see one snag.
There was a Playstation version of Civ. Persuading Sony to release would be a major, major headache. Not impossible - but they hate setting precedents (a lot of other people ask for source for other games then, "because you released Civ".
Don't hold your breath.