The exact day of the new Coolpix cameras announcement I believe is the key to wether we will see DSLR or mirrorless products on August 24th. Nikon Brazil for example has several events scheduled for this week (August 16-18th):
So far I have no indications that Nikon will announce the new Coolpix line this week. Adding the mirrorless camera to the Coolpix announcement next week makes sense, but Nikon will NOT announce point and shoot cameras and full frame DSLRs on the same date, because they will be looking for maximum press attention. This is why I think the mirrorlesss camera will be announced next week, but I could be wrong of course.
The IFA consumer electronics show in Berlin will take place between September 2-7 -it will be a good place to show the new mirrorless camera.