> They can’t be fired, but if they stop bringing in grants, they can face steep pay cuts and lab closure.
This describes the situation of tenured faculty (who are definitely who I had in mind when I referred to splashy big names), but universities have long been moving to a model with as few tenured or tenurable faculty as possible, where some instructors are full time but non-tenure-track, and others are part time (and so, for example, don't have to be paid benefits). At my university these are called lecturers and adjuncts, but other names exist. Both jobs involve renewable contracts (of different lengths), so they need not even be fired, just not have their contracts renewed.
While faculty basically no matter how useless can never be fired.
"can't be replaced" has two opposing meanings in your post.