No one's yet managed to coherently explain how the leak could delay the trailer.

The trailer is the first look for most of the people who might buy the game and is therefore tailored around creating the best first impression. My hypothesis is that because the leaks are now the first impression for most people, they might very well change features of the trailer to contradict a somewhat messy first impression.

Yes, all of us know that the leaks are not what the final game will look like, but sub-consciously we associate those low res , pre-alpha leaks with the game now and that's not ideal from a marketing perspective. This isn't an uneducated guess, it makes sense for them to delay the trailer for this reason.

With that being said I'm 99% sure the game itself will not be delayed because of the leaks.