If Apple didn't do it, even given their huge Engineering resources, I'm willing to bet that it would be either very, very difficult for an individual to pull off, or would have bad side effects like killing battery life.
While it'd be well nigh impossible as a DIY project, my bet is that all the design and engineering work on BL keys was/is already done during the Rev D redesign and can thus be implemented as a running change for a future update.
In other words, it's not something Apple has to go back to the drawing board on—it was a planned omission.