It would actually be kind of cool for humans to move to Mars and create an environment sustainable of life. It'd be the first time humans of any kind got to not only watch the creation of a new world, but be involved in it.
The sad reality about moving to Mars is that its size would not accommodate us all. By time the technology would allow us to fly there, the Earth's population will probably be double what it is now and so only the richest of the rich and most imporant would be able to escape to Mars while the rest of the humans died from whatever is forcing mankind to venture out.
