I'm afraid this may be the very end of manned space flight...
...for America, anyway.
As America becomes more and more socialist economically, the greater political pressure will be for the expansion of benefits to the growing dependent class at the expense of other traditional expenditures by the state such as on defense and space exploration. That, combined with the lack of a clearly definable goal for the program will cause NASA to retract to but a minor government-run R&D firm.