As a general idea, the only path that is badly oversubscribed is the last mile. Hence why DIA is sort of popular in the core sites but I’ve seen dozens of companies using consumer broadband. DSL, Cable, Wireless, 4G/5G or whatever they can get. A good SDWAN product selects paths around the brownouts or circuits with high drops/low latency.
In which case SDWAN is probably a rounding error for you. People with IRUs make money from them or have absurd requirements.
Not sure what an IRU is. Not heard that before ?
Like I said, a narrow use case. The vast majority of network connections have no specific requirements for low latency. It will become increasingly expensive as fewer customers use MPLS. MPLS services are already sub-scale and will get more expensive as customers abandon services.
Indefeasible Right of Use.