I believe Luffy declared he has conquered/taken over the AL. If he married Hancock as a byproduct I'm OK with that, but marriage alone is not newsworthy I think.
Why do I believe that declaration?
1)The original gathering point was in the SA, or whatever it's called, the place where Luffy punched the noble and whole crew vanished. That place is not safe, so they need a new place where to gather.
2)AL is perhaps the safest place for Luffy and Strawhats right now. They can be there safely, and there is no force available in the world what can take on the AL warrior nation. Notice the keyword available. WG can't make multi-admiral assault forces because of chaos caused by WB's announcement and death, and pirates can't either for the same reason.
3)But how can Luffy re-direct Strawhats into coming to the AL? By letting the world intentionally know about something he has done on AL island. Marriage, conquest, anything is fine. This way Luffy gives Strawhats a new gathering point.
4)Amazon lily gives a safe place to wait and train. The place is full of talented fighters of all kinds, Haki and regular kind, and it's an ideal place to wait and recover and train without being disturbed. For example Haki training would be especially beneficial for Strawhats, since it's an unexplored territory and it would give a new way to improve themselves and give new power. It would also be open to gradual improvement since I'm sure learning Haki isn't an instant process
5)One argument against this theory is that it causes too much trouble to AL to be worth it. Well, If Hancock stays behind to protect the island with Rayleigh, then there will be no problems. Hancock and the warrior nation itself is strong enough to take on almost any force out there that may want to invade, but if you add Rayleigh to the equation it becomes extremely bothersome for anyone to try and conquer the island.
I'm sure Rayleigh and Shakky (or whatever is her name) are looking for a nice island where to retire to :) So moving to AL is not a problem really as far as I see. And if Boa stays behind, no trouble will become to AL.
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So in short, I believe the "news" is an announcement about something concerning Luffy and AL, it doesn't matter what it is as long as it gives the Strawhats a safer place to gather into. And perhaps even train.