I can't imagine they would make an announcement of such magnitude on a livestream without hyping it up properly.
No "expect great announcements" or "look forward to multiple world premieres"?
Then hardly anyone will watch (in comparison to a hyped up event) - and for the few viewers you wouldn't waste any megatons.
I mean...they did exactly that when they revealed the Series X at the Video Game Awards.
We know the game exists, so when would there be a better time to shadow drop that motherfucker on Game Pass??? Would be very spicy, especially considering how big 007 is on the other side of the pond. It's not like it's a crazy remake of Goldeneye or anything, it's still an old fps, it just has better graphics, switchable on the fly like Halo Anniversary was, assuming it doesn't stray too far from the 360 version.
One has to assume they put an extra bit of work into what the 360 version that leaked a while back was, and I wouldn't expect anything too far beyond what's already out there, but you never know.
Announcing and shadow dropping it on August 25th doesn't sound too crazy, especially considering all the news that made the rounds several months ago about the new achievements being popped by a dev. A rumor that I have heard passed around a few podcasts is that it(the N64 version) is also going to be coming to Switch as well.