We have been told this will be the first time the sedan comes first. IMO I think this would work well for BMW as it will allow them to sell more sedans than before, increasing it's business case going forward into the future. I think many people just won't want to wait and will buy the 4 door immediately. I still think the sales will be predominantly M4 though in the long run. Sedans on US shore in spring of 2014 after being shown to the public in fall of 2013. The coupe shown publicly in the summer of 2014 and US deliveries in spring 2015. I expect the EU to get the car about 3-4months ahead of when we do. Or if the stars align it will be shown off together, but I doubt that.
On the Other hand
The M5 was shown first to the public and honestly I don't know if it's on US shores yet. I have not seen one in person or on the forums for US members. It was here in Detroit at NAIAS but I haven't seen it since. I know it is at PDC but has anyone seen one in the hands of a customer stateside? The M6 is out there for sale though and that was unveiled second. Maybe the sedan will show first but go on sale in the EU first while we get the M4 unveiled second and actually get that car here first in the states.