The Space Review has this excellent essay by Jeff Foust about the future of human spaceflight.
Jeff writes about "fundamental forces driving human spaceflight policy" to alter the model of competition begun a half-century ago by the so-called Space Race with the Soviet Union.
One of those forces is the simple fact that the Cold War is over. That competition between the United States and the Soviet Union kickstarted human spaceflight, as both countries poured massive resources into their respective programs in a quest to rack up a series of firsts and demonstrate their overall technological superiority. The momentum built up in the early years of the Space Age carried over into the following decades, shaping decisions like the development of the space shuttle and space station, and even, in the immediate aftermath of the Cold War’s end, bringing Russia into the project so that its engineers could work on peaceful space projects rather than missiles for Third World nations.
However, 20 years after the end of the Cold War, the momentum that propelled human spaceflight efforts has been spent. The International Space Station is now effectively complete, and the shuttle is now nearing its retirement. Cooperation with — even reliance on, in terms of human access to the station — Russia is now the order of the day. Efforts over the last several years to build up China as a new competitor with the United States in human spaceflight have failed to gain traction, perhaps because the Chinese government does not appear to be particularly interested in racing the United States to the Moon or elsewhere. While China does have plans for space stations and perhaps, much farther in the future, human missions to the Moon, their program has been proceeding at almost a glacial pace: the last crewed Chinese spaceflight, Shenzhou 7, was two and a half years ago.
Debates over the future of human spaceflight, particularly NASA’s role in it, will continue for years to come. While the overall outcome of those debates remains to be seen, one thing is certain: the next 50 years of human spaceflight will, by necessity, be very different from the first 50.