With only one government owned destination to visit, I'd like to hear the business case that results in more than one commercial crew provider. The ISS can support six crew. Assuming crew rotations similar in length to the current 6 month expeditions and three person crew vehicles, there will be 16 launches between 2016 (when the commercial entities are likely ready to fly according to the NASA deputy administrator) and 2020, the planned ISS retirement date. Any company must recoup their investment over its share of those 16 flights. Note that this neglects the Russians, that any increase in crew size per launch reduces the number of flights, and that having more than one provider dilutes the pool. Once the current crop of companies do the math, the number of bidders will fall.
The companies will gain some efficiency from leveraging their cargo launchers, but that automatically reduces the field of competitors for crewed launches. There may be non-governmental entities that alter the playing field by providing additional destinations, but the question would then be what their business case is.
The end result will likely be one heavily subsidized company that the government will not be able to let fail.