Travel between planetary bodies is painfully slow. Maybe 20-30 years we will have tourism between low earth orbit and the moon. I mean, like airplane fare level not “I’m richer than you” travel. Between mars and the gas giants will probably be another 50-60 years when we start mining asteroids and gasses like helium and such. We will still be using fuels like now, only we will be making fuel in space and working in orbit, but this most likely be automated and controlled by humans on earth/moon/mars.

Cowboy Bebop, things like terraforming and artificial gravity, etc. who knows. Science Fiction has surprisingly caught up with science in many elements of the genre. But man, I’d say maybe 400 years is a little optimistic but also possible with the way tech is moving.