Being realistic is one thing but completely giving up on pushing out the frontier of our capabilities is shameful IMO. Literally mailing it in isn't a substitute for space travel.
1) Access the vast resources available elsewhere in the Solar System.
2) Move most polluting and destructive heavy industry off of Earth (this will take big advances in propulsion technology).
3) Provide good habitats for humans and ideally much of Earth's ecosphere elsewhere in the Solar System. Certainly the human population alone could rise to the hundreds of billions if desired/needed.
Surely it'll take a lot of progress to achieve those goals, but they're within reach of our current scientific knowledge. Interstellar travel, on the other hand, is much more of a stretch goal! ;-)
We carried the seeds of our civilization to new continents which carry our gas mixture, food resources, temperature, gravity, and a million other parameters that the human body plan needs. The destinations were completely hospitable.
Good luck in space. It is beyond hostile and offers nothing for our survival. Also, there's really no economic reason to go there.
Space belongs to the robots.