Spoiler time! Loads of good stuff squeezed into such a short promo. Fantastic.
Given the way the shot of Bond entering the (supposedly) new M's office is framed, I wonder if there's any chance they won't show who he's talking to, and "007 reporting for duty" could be the last words of the movie.
You know what, i wouldn't be surprised if this was the case.
I think you have struck the nail on the head with the ending.
With regard to the little red button, how many times does M have to say 'are we there yet?' before bond thinks about the ejector seat?