Dont they tease the free update features a couple days before the stream?
They have hinting a bit towards whats in the dlc in the past, like the bathing/capybara
The update announcement has been the day before they announce the DLC for a long while with minor exceptions: The Conservation pack was announced the day before the update was announced (announcements were still 1 day apart) and the SEA and Australia packs were announced 2 days after their respective updates. The South America pack was announced ~5 days after update 1.2 but I think that's too far back to really "count" at this point.
Worth noting that there have been rare instances where they teased a feature ahead of the full update too. Custom Billboards were announced ~5 days before update 1.5 and the SEA pack. Height maps were teased ~7 days ahead of update 1.7 and the North America animal pack. Given that these were the first two animal packs, I'm wondering if they were feeling nervous about fan response to a lack of scenery pieces so they were trying to hype up the free features to balance it out. Because that hasn't happened since.
In reality, it's probably mostly about the way it works on social media, getting people talking about it, etc. So this 1 day between update and announcement is clearly working and it's fair to assume that we'll probably get the update and special stream on the same day. It's not 100%, but it's certainly a very high probability, I think!
So I need to take back my own guess that we'll be getting a feature update ahead of the full update breakdown. But still think Monday is possible. So I'm going to stick with that even though I think the Tuesday-Friday schedule is more likely, haha.
I would absolutely love to be in the Frontier office around release time. It would be fun to know what was coming and when, and watch the community guess and freak out. I’m sure it’s stressful and exciting for the team - they must be looking forward to seeing us enjoy the new content.
I agree that it’s probably going to be a Tuesday/Thursday/Friday schedule this week. Hyped!
I’m super curious about the new update too! I hope we get lots of new stuff this time around

.
I've often wondered if they read threads like this and comment about how "off" we all are with our guesses, haha. Wonder if we'll ever get insight into that (e.g., after development ends). Probably not, but I'd love to know what the energy is like at this point in the cycle.
I'm looking forward to learning more about the updates too! There's always
something in there that gets me hyped. I don't always wind up using it (height maps, anyone?) but seeing what they've done to increase the flexibility, make the game more user-friendly, enhance or add in-game systems is always a big part of the fun - as is speculating how these things might actually work in-game!