With the currently announced spacex and nasa plans, It seems reasonable that we could achieve this. The only question is whether we can develop autonomous infrastructures. People simply living on Mars does not equate to their independent survival. Astro agriculture becomes the difficult part. Can we sustain sustenance and infrastructure independently? Only time will tell, but it is my belief that 80 years is a reasonable amount of time to develop self-sustaining colonies, however it will require a massive scientific and engineering effort.