God's Age of Grace is dependant upon man's
opportunity and ability to repent (metanoeo) towards God.
I personally believe the only event that will cause God the Father to end His Age of Grace, will be the implementation of the "mark of the beast" in all the world.
It is the only discerning factor that will determine whether people will trust that evil satanic system, or trust in Jesus/God for their provisions in life, both physical and spiritual.
In either case, once the personal decision is made for one to take "the mark", and does so, the opportunity for God's free gift of salvation will be forfeited in that moment.
It truly will be the separation of the sheep from the goats.
I know that this is believed by just about all Christians and you folks might be right. But I'm from the school who believes that the events you describe may happen on the earth after the return of Christ.