This is one game I'd love to see done, though I think it won't happen, because of the real-time hype to it. But I think Fallout has shown that turn based can make a come back, and Final Fantasy Tactics has shown that as well. And finally, this outline from Chris Clark for a sci-fi, future earth game called EdenQuest. It is the year 2086. Despite the technological advances of the 21st century, the Earth is struggling to survive.
Humans are now the physically largest mammal on the planet.
Food shortages are common and natural resources are almost entirely depleted. All countries have voluntarily or involuntarily joined the Earth Governing Council. The only war now waged are the battle to save a dying planet. A large group of environmental terrorists calling themselves the Children of Gaia routinely destroy refineries, factories and EGC buildings. However, even in this bleak time there is excitement and hope.