They actually can become corrupted. For example, Malthael’s original plan (or so Balzael believed it to be) was to leave the Black Soulstone in the High Heavens long enough for the Angiris Council to become corrupted enough so that they would vote for Sanctuary’s destruction. And until Tyrael and the Horadrim stole the black soulstone from the High Heavens, it was indeed corrupting the High Heavens, including the crystal arch (as it spawned a corrupted angel), as well as the angiris council members (Auriel herself admitted to this). That said, it likely takes a significant amount more time and effort to corrupt an archangel in comparison to an angel.
While that can be taken as an implication. The series itself simply treats Tyraels revival as an extreme oddity.
No, even if an angel had suffered from corruption, their death will lead to them being replaced by a new angel. The only exception is if the corruption was great enough to grant them major demonic traits, in which the Angel would now respawn in Hell like any other demonspawn (Izual is an example of this).
More than likely Malthael will simply be replaced by a new Archangel. Only way he’ll return is if he suffered great corruption (in which he’ll be a demon) or Malthael had designed a contingency plan in the case that’s defeated in order to assure his eventual return. If neither occurs, then Malthael’s gone.