Technology acceleration occurs after economical tipping points. The cost to get mass out of earth's orbit is still way too high to justify large movements of "settlers." We need a paradigm shift. The paradigm shift could occur lowering the cost of energy (extremely cheap solar, fission, fusion, or ? power). Or it could occur by breakthroughs on the cost/energy required to leave orbit (space elevator, other?). Meanwhile, as virtual reality and ultimately cheap virtual immersion becomes commonly accessible, the need for travel will continue to decrease. When virtual presence rivals real presence at a fraction of the cost, real human travel becomes a luxury that only becomes necessary for exceptional reasons. And that goes even more for space exploration. Only actual settlement (vs exploration) really requires humans.

I believe ultimately a tipping point breakthrough will occur and settlement off earth will begin. Once it starts I see no reason that we would not have trillions living off planet in either constructed habitats or other asteroids/planets. Even if we did not have a major technology breakthough, ultimately we would bootstrap (live off the land) type of settlements that would grow off earth. It would take much longer obviously, but I believe it would happen. Under either scenario we would(should) send very advanced robots to do most of the hard work.

All the predictions of easy space travel in this millenia were based on some sort of very cheap propulsion that we would develop. Obviously that hasn't happened. At the same time computer technology and virtual reality were not anticipated by many of the dreamers in the same era that were dreaming of cheap space travel. So, a lot of exploration is getting done (by smart probes) instead of humans. Different but in many ways the same result as far as the information gained.