I don't believe the parable of the prodigal teaches universalism. But it does teach the Father's undying love for his children. Is not God the same yesterday, today, and forever? If God can deliver in life...is he incapable of delivering in death? Take into consideration the Dispensational teaching of Christ setting all the souls in Paradise (Abraham's Bosom) free who died under the Old Dispensation and how the gospel was preached to the dead during the three days that Christ was in the heart of the earth.
God doesn't ever change...
Romans 8:38-39
38For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come,
39Nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord.
Just a thought.