No other planet in our solar system is remotely hospitable for human life; whether it’s Mars, Europa, the upper atmosphere of Venus—or anywhere else that’s been proposed as a possible colony.
Any move to an alternative celestial body requires a lot of technological intervention to sustain an environment for human habitation. And that means that it’s easier to do the same on Earth, regardless of the conditions here.
There are some astronomically long-term events that could mean having to evacuate the Earth. One scenario is Mercury being pulled out of its orbit by Jupiter—and then possibly colliding with the Earth, or at least affecting the orbits of the inner planets in chaotic ways.
But there won’t be humans around in hundreds of millions of years anyway—not as we are now.