If the pope fires Cardinal Sarah (i.e., removes him before his term is up), that will cause a stir; if he does what SecretSeminarian suggests he might do (not reappoint him when his present term expires), there will be less of a stir in that the pope seems not to want the curial prefects to stay too long.  If there is any fanfare, it will not be of the pope's making; he's just doing his job.
Rather than grasping at their curial sinecures, the prefects ought to be grateful to the pope for relieving them of the burdens or bureaucratic pencil pushing while they're still young enough to do something else.