It isn't the potentiality of their forgiveability. It's simply that, if God made everything, including us, then He is able to apply redemption to those who chooses, and pass by the rest. A sad, but at the same time beautiful, metaphor is that of a grain of wheat. The unsaved are like the outer chaff, They are needed to preserve the germ so that, when the time is right, the germ will sprout. The chaff, too, have great value, even though their ultimate destiny is not to eternal life. They, too, are important, God's handiwork.
God works this way, I truly believe in my heart, making all things work together for good to those who love Him.