Luffy still looks to be an active pirate. I imagine he goes from place to place, meeting new people, visiting bars, and fixing local troubles. Kinda like an extension of what Shanks did in the first chapter.
Zoro could still be traveling with Luffy, trying to hone his skills, while incorporating new styles like Yontoryu and Gotoryu. Alternatively, he could have become a teacher back at the Isshin dojo, possibly with Tashigi, who both inherited it from Koshiro after he passed away.
Nami is conning people based on her dialogue, so maybe she's still a thief. She seems like the most likely to still be traveling with Luffy due to her dream of making a map of the whole world, and there's still 3 other seas she hasn't explored.
Usopp appears to be reminiscing about the other Strawhats. My guess is he's back at Syrup Village, telling stories of his adventures with Kaya.
Sanji definitely takes over Baratie from Zeff. Since I believe the Red line dividing the world will be destroyed, the Baratie can finally, truly fulfill its dream as a roaming restaurant. Sanji could visit places from Foosha Village to Wano, serving all kinds of meals made from all sorts of fishes. Hopefully he has a companion chef with him like Pudding. Sanji is the most likely to be a father as well, and if he had a daughter, would spoil her rotten, and if it's a son, he'd treat him exactly how Zeff treated him.
Chopper is a doctor who can cure anything. Meaning his services are needed all over the globe. He might be traveling with Luffy to accomplish that, or going out on his own to prove he can fend for himself like a real monster. Another alternative is that Chopper takes over the Isshi-100 from Dr. Kureha and trains them in his ways, and the organization expands globally. Certainly more manageable than being a sole roaming doctor.
