Cooperation changes the game. Nice. With the terraformers buying you a couple of extra years, you might be able to get significantly more people offworld... IF you find a habitable planet in a nearby system. Or, you know, 6 of them since that is how many empires there are.
It is quite ironic, Sol would be an amazing home system if it wasn't for the cooling sun. 0.9 sorium gas giant, venus with tons of minerals, even ruins on mars. I can see a cold, dead Sol still being exploited for resources, fuel, industry and alien artifacts for a long time to come.