Dawn is probably delayed until the endgame. Wano opening probably happens near the same time as Fishman Island emerging from under water. Through Shirahoshi/Momo commanding Sea Kings/Zunesha.
I think the last panel of One Piece will be the Sunny sailing into the "dawn", as the crew go on in search of new adventure, subverting the old trope of sailing into the sunset.
I actually don't like the crew going on another adventure.
Just because there's a few scenes in my head that i would love to see:
Sanji taking over the Germa 66 army and those moving castle snails to make huge Baratie 2.0 for Zef and the old crew, so they can keep making food from the new created All Blue.
Zoro resting in Wano drinking Sake, and Momo coming to challenge Zoro for the WSS title, and also Enma.
Stuff like that would be dope as an epilogue.