The information below includes the opinions of scientists and space analysts inside and outside NASA. Details attributed to the White House are drawn from internal position papers obtained by Space News and SPACE.com."
Here's a FAQ with details on Bush's vision for NASA. Considering the mothballing of NASA's shuttle fleet and the potential rise in commercial space access. NASA astronauts could be destined to take commercial flights to the ISS within the next 20 years or so.
With frequent commercial trips to Earth orbit, lunar, near Earth asteroids, and Mars will be much easier to reach. Perhaps this could accelerate NASA's goals over the next few decades. NASA would be working less on the infrastructure of space travel and focus more on the medical, industrial, exploratory, and astronomical sciences.