I am reminded of the assertion (incorrectly attributed to Lord Kelvin) that the start of the 20th century would see the ??end of physics.??
??… years earlier, Albert Michelson ??whose famous experiment with Edward Morley refuted the existence of the luminiferous ether?? said at the inauguration of the Ryerson Physics Laboratory at the University of Chicago that the great principles had already been discovered, and that physics would henceforth be limited to finding truths in the sixth decimal place.?
(See: https://www.bbvaopenmind.com/en/science/physics/lord-kelvin-and-the-end-of-physics-which-he-never-predicted/ )
While the scale and resources devoted to the effort to bring about the original NAD 83 project will never be repeated See: https://www.ngs.noaa.gov/PUBS_LIB/NAD1983_Collection_of_Papers.pdf there remain numerous and many unforseeable challenges for the greatly reduced ranks of the NGS.
In my opinion the work of the NGS is diminished by its inability to move beyond relying on the kindness of others for its observation data. The piece wise, state-by-state approach which led to great variations in monument densities and time periods of observations (with a number of years separating state-wide surveys.
Given declines in the the willingness of nations to cooperate on all many of activities, I wonder how long the international cooperation represented by the IGS and similar components of international geodesy will continue?