I doubt that very much. How large a population can earth permanently support? Certainly not an unlimited number. There is also the possibility of an ELE such as an asteroid or commit or a massive CME etc. You also may not be aware of the fact that the earths magnetic field is steadily decreasing, if it continues at the present rate it will be gone completely in 1000 years, this protects us from the solar wind, as it drops off near nothing the atmosphere will begin bleeding away into space, this may be what happened to Mars. It is very possible that the earth will be incapable of supporting life in as little as 1000 years, although I would expect us humans to cause such a problem long before nature does. The sooner we start colonizing space, the sooner we can be sure of survival of the human race.
Let's get the hell outta here!
Alan