There is no separate plan, God did not fail ... One Plan.
True, it was His chosen people who broke the covenant time and time again. However for those who were believers, He certainly kept His Word.
For the others, they were not blessed by some physical relationship to Abraham when they went to Hell.
For example, one time Moses returned from speaking with the Lord, and the rebellion took place. The Lord opened up the Earth and swallowed up into Hell many descendants of Abraham.
We ask ourselves, wait....what happened to the blessings of being in that lineage??? Wasn't it an everlasting Covenant?
It was conditional on their part.
God kept His promise to those who called upon the Name of the Lord for salvation are in Heaven to this day.