How does SD-WAN complement MPLS?

MPLS and SD-WAN are often pitted against other. It's a false dichotomy – in fact, SD-WAN technology is often used to augment MPLS in a hybrid WAN architecture. The MPLS market is still huge, despite its expense and its limitation for accessing cloud applications. Based on various forecast sources (e.g. IDC, Grand View Research, Research and Markets, etc.), in 2018 the global MPLS revenue is slated to exceed $15 Billion. Telecom operators keep MPLS prices high as the service gives enterprises predictable and reliable private network connectivity. While it's costly and infeasible for meeting enterprise needs for multi-cloud access, MPLS functions seamlessly within an SD-WAN architecture alongside internet links, especially between headquarters and larger remote offices. Even those enterprises that intend to eventually eliminate their MPLS WANs usually begin SD-WAN deployment with a hybrid architecture, avoiding the need for a "rip and replace" forklift upgrade, preferring instead to eliminate MPLS after 12-18 months, perhaps when their MPLS contract expires, or when sufficient network reliability has been proven with the deployment of failsafe SD-WAN technology.