ISS's reason to exist went away when the Shuttle was mothballed. The ISS was, in turn, the reason to keep flying the Shuttle. They tried to come up with a similar dodge for SLS, in the moon orbit base, but SpaceX pulled the rug out from under that. That would have been a boondoggle of dven more epic proportions than STS/ISS.
We still need to find a way to shut down the F-35 without needing to cancel all the subcontracts let for parts of it. Without saving those, it will never be allowed to die. (Using the afterburner destroys parts of the rear control surfaces, that have to be replaced at a cost of, what, tens? hundreds? of $thousands after the flight... if it lands.)
This is a popular idea, but it can't really be proven. The decision to have ISS comes from many people and countries, and those people have different reasons - including, among others, employing Shuttle, former Soviet engineers and an accessible space outpost to conduct space experiments.
Who needs government sponsored science? All hail the Musk!
"I said ship it!"
Luckily, no one is responsible if things go wrong!
