Anyone who's been to Langley may be aware that NASA proposed this concept in the late 90's, even including the RTLS maneuver for the booster, but Bush/O'Keefe/Griffin quashed all work on reusable launch vehicles in favor of "Apollo on Steroids". The idea of reducing the cost of spaceflight to actually make it practical did not seem important to them. I wish the DOD luck but they may face funding cuts as well and may abandon this program when it has to compete with combat systems. NASA will have to beg a junior partnership, and since the program is now classified, even if it is successful it will be decades before it will be available for commercial purposes. In the meantime the lessons of Shuttle will be forgotten as the workforce is dispersed. Say, when did Congress vote to cancel the Shuttle?
Recently some brave souls at JPL and DOD proposed a low-key partnership to investigate RLVs but it has a low budget and whether it will win support from higher up remains to be seen, particularly since the program formerly called Constellation is apparently still proceeding full bore under the protection of its lobbyists.
The majority of people in the space program whom I have asked about the economics of reusable launch vehicles think that the Space Shuttle "proves" RLVs aren't practical. When I ask them why Apollo was canceled, or why we built the Shuttle in the first place, or why Shuttle costs so much more to operate than was specified, or how Constellation can ever produce a positive cash flow given its extremely high operational costs, they look at me with a blank stare. Apparently these questions don't seem important. Sorry if I sometimes seem cynical.