Cross-border payments are transitioning from bilateral corridor models to multilateral ecosystem architectures, with regional examples including PAPSS in Africa, Project Nexus in ASEAN, and Al Etihad Payments in the UAE demonstrating that shared infrastructure outperforms an ever-expanding web of bespoke bilateral connections. Institutions that build or join multilateral ecosystems gain strategic advantages through unified operating layers managing routing, compliance, and liquidity across multiple payment systems at scale.