For new and/or at the dealer, I heard, maybe in the next week(s). For existing owners, notices go out in January. It appears that the safety thing is being addressed with a software tweak to adjust how fast and when the airbag inflates, so it's not a separate hardware change, so it should be easier to implement. There's a similar one already in place in case there's a child seat on the passenger's side, so, it appears the ability to do this may work on the driver's side as well.
No idea on anything regarding the REx. Hadn't heard there was a hold on that or what the issue is.
2011 535i x-drive GT, 2014 i3 BEV