I agree with this...especially since it's only using 3G bandwidth. I doubt Tesla is paying per MG/GB downloaded. All data and information that the car can download is a drop in the bandwidth bucket.. and slacker and other audio streaming services are compressed, so I really don't see a few thousand cars, pulling a few hours/days of streaming audio to really amount to much that either Tesla or AT&T would even blink an eye at.
Their contract with AT&T could charge them for bandwidth, we don't know. If it doesn't, however, there is likely a clause on excess usage and such.
In the past 2 days my P85D and P85 combined have eaten roughly 1.3GB of data from Slacker. So, lets say 650MB per car, so 325MB/day/car. This is low because both cars were away from Wifi for good periods of time in the past couple of days.
Lets say conservatively only 10,000 Model S have the bug and are not on WiFi.... that's 3,250,000 MB, or 3.25 TB of bandwidth PER DAY. Keep in mind that this is in addition to any normal data usage the car would do.
The average American drives 12,000 miles per year, so, ~33 miles per day. Lets say that 33 miles was done at 45 MPH, so a driving time of 44 minutes. We'll round to 45 minutes for simplicity. The Slacker MP3s I see in my WiFi traffic are 128kbit, so, 45 minutes worth would be about 43MB. So we'll say normal usage is about 50MB/day, give or take, on average for a slacker listener. Even if we double that to 100 MB/day the car is still eating over 3x that on it's own with this bug.
I'm pretty sure that is something Tesla and AT&T will notice.
Edit: I'll note that the above portion of the issue is Tesla's problem and won't bother 99% of users. However, the fact that the car stays awake while this is happening, and thus eats energy, is the end user part of this bug.
My assumption is that this is not just a bug in the media app and is related to energy saving/sleep in general.