More on the Orbital Space Plane
While government agencies are generally bureaucratic, corporations are also notoriously short-sighted. Excluding all the information satellites and the like, there isn't a whole lot (to my knowledge) that will make space profitable until we cut the cost (not in dollars, but in resources) to actually get into space. Mining asteroids might be feasible, but I doubt even that would be profitable in the very near future.
If, as you suggest, the government provides incentives for these companies, they'll become no better than NASA, since they'll be leeching off the government's funds, doing nothing more than "putting a guy in space".