“Each of these Catholic Reformers retained the unity of Christ’s Church, submitted to church leadership, and patiently brought about renewal”
Hypothetical: Would it be possible for the Roman Catholic Church to reach such a level of corruption that it was cut off or discarded by God?
No. The Church is Christ's bride (Ephesians 5:29) and has "no spot, wrinkle or blemish" (Ephesians 5:27). Christ also stated that the gates of Hell will not prevail against His Church (Matthew 16:18) so how can the Church commit error? Individual clergy may commit sins, even popes commit sins because in the Church there are both "weeds and wheat" (Matthew 13:30).
Following your wording-No. Is there a level that would bring such action by God? Surely, but the Church cannot reach that level. The historical upwelling of reform from within is the what maintains the Church. God is working with fallible humans whom he has endowed with free will. He does not cut them off for small deviations or reparable corruption which is inevitably repaired.
You wrote:
“Hypothetical: Would it be possible for the Roman Catholic Church to reach such a level of corruption that it was cut off or discarded by God?”
No. The Church comes from God. The Church is never corrupt - people in it often are, however.