venus is a bellwether of earth' future. In the first several billion years When the sun was a dimmer less hopped up star, venus was in the habitable zone and there is strong evidence that there was liquid water on that planet. This fluid is gone from the surface as venus's proximity to the sun had negative results (for water and probably life). Runaway greenhouse effect indeed. Its the grandadsy of that phrase
The sun is building up stash of helium that will wvntually cause its expansion into our habitable zone and we will be going the way of venus. SO, terra forming Mars or a moon of Saturn or Jupiter may give us a couple hundred million years of life as the sun grows into a huge hot orange ball fusing helium as its final trick. Hopefully by then we will have gotten it and have the interstellar dimensional thing worked out. Otherwise our individual progeny wont hve as extended a future as was mathematically predicted.
But, what the hell, if it wasnt for deadlines , nothin would happen.