The rationale behind HydraLink is that the automotive sector is undergoing a shift from CAN-based systems to advanced Automotive Ethernet networks like BroadR-Reach (802.3bw) that allow multiple in-vehicle systems to simultaneously access information over unshielded single twisted pair cables.  So as I understand it, the HydraLink is the modern equivalent of OBD-II USB scanners relying on Ethernet instead.

I thought I’d be retired before CAN was phased out for its primary application. I prove once again I’m terrible at predictions.