The logistics of having an exodus making a significant difference are somewhat difficult though. Consider the current birth rate of 350K new humans per day and compare with the lack of orbital launch capacity. Then try to figure out how to reach the manufacturing capability to build hundreds of city sized starships per year. One of the variables is going to have to change in some way or spreading across the galaxy isn't going to do much to reduce earth population.
Well, maybe someone will find a couple of dozen stargates tucked away somewhere.