  It is widely expected that generic black holes have a non-empty but weakly
singular Cauchy horizon, due to mass inflation. Indeed this has been proven by
the author in the spherical collapse of a charged scalar field, under decay
assumptions of the field in the black exterior which are conjectured to be
generic. A natural question then arises: can this weakly singular Cauchy
horizon close off the space-time, or does the weak null singularity necessarily
"break down", giving way to a different type of singularity? The main result of
this paper is to prove that the Cauchy horizon cannot ever "close off" the
space-time. As a consequence, the weak null singularity breaks down and
transitions to a different singularity for which the area-radius $r$ extends to
$0$.
