Who was the pattern of God's longsuffering intended for?
The pattern of God's longsuffering was intended for those who would thereafter believe on Jesus Christ. God extended mercy and grace to the chief of sinners first, so that everyone else from that point on who believes might have life everlasting.
Les explains that God extended mercy and grace to the chief of sinners first—the one at the head of the line—so that in him God might show forth longsuffering as a pattern. That pattern was intended for those who should hereafter, from that point on, believe on Jesus Christ, and by believing have life everlasting. Les also ties this to Paul as the Apostle of the Gentiles, the one to whom the mysteries were revealed, who always defended his apostleship.