"..or what intermediate steps have to be taken.."
This is always a problem: incrementalist thinking, the idea that one can achieve the revolutionary through small intermediate steps with an evolutionary process. This is very limited (and limiting) thinking, and people who think that way will never achieve anything truly revolutionary. If you think like this, you should probably get the hell out of the way of those of us who don't. We'll come back for you. Some day. Maybe.
Revolutionary v.s. evolutionary is a false dichotomy. Some of the most revolutionary developments have been incremental by nature, but each increment could also be seen as a minor revolution.
Think of the miniaturization of electronics, or Moores law. Each year businesses that make CPU:s, GPU:s and other chips make incremental progress, but most of those increments required some (relatively minor) revolution in the way that one thinks about chip-making.
Rockets went from tiny fireworks in the late 1800:s to the Saturn V in the 1960:s through incremental progress. Then the US tried and failed at switching to space shuttles. Now it's back to rockets again, and incremental work towards better rockets. Some of those increments could have a huge impact, like being able to re-light the first stage and land it for later re-use.
Maybe one day it'll be space elevators instead of rockets. Maybe. Keep in mind that there is no guarantee that a space elevator will be better or cheaper than rockets. That largely depends on how expensive it will be to build the elevator, how often it will need maintenance and how long it will ultimately last until you need to scrap it and build a new one.