This is needed. Is there an sd card slot somewhere?
There is USB. I bet Tesla could charge for this as a separate option too. Challenges however would include, but be limited to:
* making sure the storage is fast enough. People would plug in cheap drives and then complain. Maybe the car could detect that the card is in not keeping up, but even then the issue would be that people will complain why it's not working and conspiracy theories would bloom on how Tesla is forcing people to buy an official Tesla approved USB drive for $300 by making their $15 drive not work well.
* picking which camera's to record. I suspect no USB drive would keep up with all cams footage. I know my dashcam with just 2 cameras already needs a premium rated SD card to keep up 24/7 and in various operating temperatures. I guess you could let the user pick up to 2 or 3
* recording this much data real-time would use up system bandwidth and processing power which could be used for AP functions. I doubt people would like to choose between the 2 functions.
The devil is in the details, as usual. Now the last question would be is it worth moving engineering resources to this. How much would people pay for this and what percentage of people would buy it? Say adding extra hardware to handle this much recording added $500 worth of hardware (remember that automotive grade hardware cost more), then with all the software development their total cost is $1000 per car, so retail $2000. Then add another $500 to pay for the hardware on cars where people don't buy the feature, $2,500 option and that's before storage cost which could cost as much as $300 for a hardened 128GB stick. So approximately $3,000 which likely not many people would be willing to pay for.