There have been challenges in CRD/DTR/PAS/CDex around:

• As a provider, how do I find out the payer CRD/DTR/PAS/CDex endpoints to use for a member (including how my local payer build may not be at the right granularity if I've configured things with catch-alls like "OUT OF STATE BLUE")?
• As a vendor/clearinghouse/QHIN receiving a FHIR Coverage/Organization that only contains provider defined identifiers, how do I figure out who that payer actually is and where to route the message? 

To deal with this, there have been discussions about trying to figure out various equivalents to a national payer id, or plans to wait on CMS hosting a national directory of plan IDs and endpoints- that have run into various issues or are too far out to help implementers. 

The current leading discussion is a plan to have payers just return a well known endpoint that consumers could uniquely recognize and use to figure out all the other endpoints that their use case may need. It would be returned within the 271 (PER segment) and downstream be exposed on the FHIR Coverage resource. This ticket tracks discussing this idea further and more discretely defining the plan in HRex.