Back in the kick starter days, Blink planned on using the USB port to store videos locally. The idea was videos would be stored on a flash drive as a backup when Internet was down. It was a great idea but I suspect they found it too complex to implement. More recently they proposed a sync module using the cellular network as a backup. Haven’t seen much on this plan and suspect it too has been put on the back burner.
I don’t think the Ethernet port was officially discussed but I suspect they found out it was also too error prone. Bridging WiFi with LAN can cause “network storms” with streaming data that only a router can effectively address. Then if it was set with either/or, could you imagine the support headache?