On the final page of chapter 1064, Vegapunk/Shaka had a conversation with Dragon, and it seemed like they talked about his impending death. This was a huge revelation, and it drastically changes things in the story.
At the time, we mostly assumed it was to establish their connection and potentially hint at some Revolutionary activity this arc. Well, the arc seems like it’s about to close and the only Revolutionary Army activity on Egghead has been Kuma (which was its own thing). He could’ve told Dragon about Bonney too, but I think the Dragon-coming-to-Egghead ship has long sailed.
I believe the call with Dragon essentially continued like:
“I think I’ll be dead soon. I just wanted you to know about this, Dragon! […When I die, a message I pre-recorded will play out across the world, revealing the truth to everyone! You must seize the opportunity and be ready to act on the state of upheaval; for Ohara, and the World!”
Or something along those lines. I’m sure Oda will be much more eloquent. I also think Vegapunk likely spilled a little bit of what he’s going to reveal, to better prepare Dragon, I’m just not interested in trying to solve that puzzle since we’ll probably find out in less than a week. But by the time our group makes it to Elbaf, open war could already be happening around the world.
No matter what, next chapter will be legendary. I’m more excited for this upcoming reveal than I have been for any single chapter outside of maybe Gear 5.
TL;DR
Vegapunk wanted to let Dragon know he was about to reset the board by revealing the truth of the world by way of his death, giving Dragon just enough of a heads up to act on whatever state the world finds itself in post-reveal.