God promised Moses that He would give a number of nations into Israel’s hand at a future time when their sin would be ripe.
Genesis 15:16 MKJV
(16) But in the fourth generation they shall come here again, for the iniquity of the Amorites is not yet full.
This implies God’s judgement and the resulting decree as to their fate. In this case, they were to be disenfranchised of their lands and Israel would take their place.
Lest anyone think that God is partial in judgement, when Israel’s sins reached a certain level, He caused great invading armies to kill many and to take the few who survived captives into exile.
This is not as arcane as it may seem. God may yet one day judge us similarly. At the time of the US War of Northern Aggression, many people concluded that the deaths and destruction were God’s punishment for the national sin of slavery.
(People who don’t believe in God, don’t accept that theory and seek to impose their own punishment for that sin. Or better yet, to just continue to complain about the sin and to leave the painful wound open and festering because it works to their ideological advantage.)
If The Revelation of St. John is talking about today, then expect similar destruction and plagues as what happened to the Egyptians to happen to the world over.