It is true that some galaxies manage to pull apart after colliding, they propel each other out further than gravity would be able to pull them back in. However from the data Hubble is providing, our collision with Andromeda seems to be kind where gravity does win.

Yeah I agree that we are just scratching the surface of genetic manipulation, but you have to bare in mind this though process I proposed here wouldn't be a journey we'd start tomorrow, but rather start building our path towards.

I believe the protein and nucleic acids in our bodies will start unfolding at temperatures of under 100 Celsius. First of all because of the weak hydrogen bonds that hold secondary, tertiary structures together which start failing at slight changes of pH and temperatures. Our bodies have not really changed much in a very long time and we had to migrate as a species towards habitable places in order to survive.

Thanks for reading and commenting, it's always a pleasure to debate such topics :)