[Crosseye_Jack]

In the “mobile first” world we are moving to (thinking about how I see more people reaching for their tablet first over their laptop even if they even own a computer these days) I could see a “bridging cache device” like you say becoming more likely.

Hell with the size of WiFi enabled microprocessors these days (something like an esp8266 paired with enough flash to hold the updates) you could prob squeeze it right into the cars keyfob itself. Though I would want the wifi processor to be separate from the keyfobs key processor.

Edit: Wireless charging of the fob so the car keeps the fob charged. When the car detects an update is available via its lte connection it wakes up the more power hungry WiFi chip in the fob via induction or something (trying to keep the “cars keys” processor separated from the WiFi processor) and a notice on the cars dash or an push notification to the cars companion phone app notifies the user of an update. If the fob knows of a WiFi station it can listen for that beacon and then download the update. If not found after a while goes into a pairing mode for connection to a phone/tablet like you say by offloading the UI.

Would need some polish to make it user friendly but yeah... I’m liking the idea.