Nationally, the promises of the Father are still to Yehuda. On an individual basis, each "Yehuda" still has to decide to return to the house of the Father (be born again, place his faith in Jesus Christ for salvation), or he will be cut off eternally.
I'm dealing with groups rather than individuals in the parable. I agree that God reserves the right to prune His tree of individual branches for the sin of unbelief.