If the Sun getting more luminous means Earth will become like Venus, does that mean Mars could become habitable like Earth?
Probably not, and the reason is that Mars does not have enough carbon dioxide to keep it warm, and it also doesn’t have much water left (although some may still exist under the surface). Furthermore Mars doesn’t have much geological activity. So the ingredients for a stable carbon cycle and climate – ocean reservoir and plate tectonics to recycle the carbon dioxide – are absent, and warmer temperatures by themselves would not create these conditions. It’s not completely understood why Mars lost most of its atmosphere and water. The fact that Mars is relatively small (low escape velocity for gas, fast cooling of internal heat reducing geological activity) probably didn’t help. The lack (or loss due to solidification of the core) of Mars’ magnetic field, which would have prevented the solar wind from stripping away and breaking apart water and greenhouse gases in the atmosphere, may have also contributed to the current cold, dry state of Mars.
