My bet
Is that we will not let HST simply go, unless there is a replacement platform. I think a consortium of interested parties, US and others, could prevail on NASA to not simply walk away.
HST is one of the great demonstrations of the success of manned flight working with big science unmanned prgrams. The terabytes of data retrieved by HST has helped rewrite Astronomy textbooks. We should not let it go because a bloated bureaucracy is afraid.
Ed