So, maybe the next steps are:

 1. Keep the current component model (MAC/PHY/MODULE) and the
    NEAR_END/FAR_END direction (naming need to change as Maxime said).
 
 2. Add a depth (or order?) field to ETHTOOL_A_LOOPBACK_ENTRY as Jakub
    suggested, local to each component instance. This addresses the
    "multiple loopback points within one MAC" case without requiring a
    global ordering. I hope it addresses what Oleksij's switch example
    needs (multiple local loops at different depths within one
    component) *insert that screaming emoji*.
 
 3. Document the viewpoint convention clearly.
 
 4. Punt on the grand topology dump. Too much to chew.
 
 5. Don't worry about DSA CPU ports - they don't have a netif, so
    loopback doesn't apply there today. If someone adds netifs for CPU
    ports later, depth handles it.

TL;DR: Add depth, document the viewpoint convention, and ship
it^W^Winterate.

Did I get that right?

Sounds reasonable. The first version can be KISS, we just need to keep
in mind reality is more complex and try to avoid adding any roadblocks
for making it more complex to reflect that reality.

    Andrew