A problem: We're years away from having a replacement (the Crew Exploration Vehicle plus the SDLV heavy launch vehicle). What do we do, cut the shuttle and then sit back for 5+ years without any access to space? That would be asinine.
The shuttle fleet was due for replacement 15 years ago, but mismanagement and politics have prevented that. That said, there are people willing to go up in it, and work that needs to be done in orbit.
What's really needed is clear and immediate funding for the CEV development, set up commercial contracts for the heavy launch requirement through any vehicle available (either Protons/Ariane V or get a domestic heavy launcher going) as soon as possible.
Use the shuttle as needed until the new vehicle is available, then retire two of the remaining orbiters (keeping one in mothballs in case its neeed). Five years after that, I want NASA out of the launcher business. They can provide 'space traffic control' services the way the national airspace system works through their existing infrastructure, but their role with the CEV should transition to a certification role at best, ala the FAA.
