I think BMW frankly doesn't have to worry with the current e70, as its EOL so frankly they would just make an oem adapter available. With the Next gen, they've probably put that in development to accommodate, and most LCIs will take care of the rest of the F-based cars.
Btw would not purchase an iPhone till the next iteration, since it's lacking compared some of the features of the S3.
In regards to the adapter, I'm guessing since most docks used the 30 pin to stream audio out, and the new adapter is suppose to Help accommodate the new dock to the old accessories, the current combox should be fine with the 5. However I'm guessing pretty soon, the per 5 devices are gonna be dropped from the next gen BMW combox, as their current no adapter to take the 30 pin to the new dock.
BMW and Mercedes Build Beta Products!
Lexus build Release Candidate Products!
Why does this matter?
CAUSE EVERY TIME someone says Lexus has better build quality, one should consider what Toyota their Lexus Engine and chassis platform comes out of and how long that part has been tested in the real world!