There is no shortage of proposals for radically innovative space launch schemes that, if they worked, would get us across the valley to other hilltops considerably higher than the one we are standing on now—high enough to bring the cost and risk of space launch down to the point where fundamentally new things could begin happening in outer space. But we are not making any serious effort as a society to cross those valleys. It is not clear why.
Sure SpaceX is the first (almost) successful commercial venture of its kind and has been a long time coming. But they're still using essentially the same old ICBM technology the USA and USSR have been using for the past 60 years.
Stephenson is advocating more energy, research and money be devoted to the technologies on the horizon that would replace giant explosive tin cans.