Yes, that was examined by Nixon back in 69-70. The varied budgetary options are discussed in Tom Heppenheimer "The space shuttle decision".I wonder if there's a possibly even more extreme retreat which literally just pulls back to 'job done, we only need unmanned rockets to stick some satellites up there now'. Which means when the President is gunning for manned missions again it's a complete tabula rasa in terms of existing designs,
Paine vision (NASA enthusiast and naive dreamer)
1. Mars by 1981 > "Vigorous or all-out": Funding increasing to $7 billion per year in the mid-1970s and possibly to $8-10 billion in the latter half of the decade, with a commitment to an early Mars mission.
2. Mars by 1986 > "Intermediate": Funding increasing over the next five years to $5-6 billion per year, with a commitment to Mars. This commitment would carry no fixed date, but the mission would probably fly in the mid- to late-1980s.
3. Mars "somewhere circa the year 2000" > "Austere": Level funding at $4 billion per year, with no commitment to Mars but with an option for such a mission retained.
Townes proposal might be there...
4. For the sake of comparison... NASA budget for 1968 was $4.7 billion, dropping to $4.2 billion in 1969 and $3.7 billion in 1970.
Robert Mayo vision (OMB = bean counter)
5. One alternatives, at $3.5 billion per year, eliminated NERVA and stopped production of Saturn V and Apollo spacecraft. This option, however, would maintain a vigorous program in piloted flight, featuring Skylab with three visits as well as six additional Apollo lunar missions. Better yet, such a budget would accommodate "Space Transportation System and Space Station module development with launch of both in 1979."
6. Two other options, at $2.5 billion, also permitted flight of Skylab with its three visits, along with the six Apollos. There could even be a space station in 1980, with Titan III-Gemini for logistics. However, there would be no space shuttle. NASA-Marshall would close, while activity at the Manned Spacecraft Center would fall substantially.
7. At $1.5 billion, the piloted space program would shut down entirely: "All manned space flight ceases with Apollo 14 in July 1970." Not only NASA-Marshall but the Manned Spacecraft Center would close, with the Saturn launch facilities at Cape Canaveral shutting down as well. Yet NASA would continue to maintain a vigorous program of automated space flight.
Even at $1.5 billion, the agency could send six Viking landers to Mars, and could take advantage of a rare alignment of the outer planets to send spacecraft to Jupiter, Saturn, Uranus, Neptune, and Pluto. NASA would conduct "at least one planetary launch each year in the decade," and would pursue "a relatively ambitious science and applications program with 95 launches in the decade."