The ISS is the placeholder but I do agree that its usefuness beyond that is dubious.
The problem is that we never seem to recover from our backsliding. Giving it up is ground that’s hard to regain.
An ongoing problem for the last few years has been deciding for what is it a placeholder? Taking men to Mars? Building the proper craft for the job which can be used for other efforts, too?
Mars may be close astronomically but it is not time wise. A craft that would significantly shorten the time probably could not be manned so what is the purpose?
I don’t favor killing NASA but is getting harder and harder to justify. It has also become a depository for graft, as have nearly all government programs, and a parking place for some liberals who use NASA to reenforce their credentials.