In One Piece, bounties are more than just a power-scaling system -- they determine how much of a threat someone is to the World Government. After everything the Straw Hats have done, they are finally becoming the world-renowned pirate group they were always meant to be, but they won't stop there.
When the Wano Arc finishes and the world finds out that the Straw Hats were instrumental in defeating two Emperors of the Sea, their bounties are sure to skyrocket. Depending on how Big News Morgans spins the information, they could end up being the one of the most wanted pirate groups in the world, replacing the Beast and Big Mom Pirates. The question is, what will their bounties be?
After defeating Doflamingo in the "Dressrosa" arc, every Straw Hats' bounty was raised by at least 50 million regardless of their feats. Since the Straw Hats helped defeat two Emperor's crews, each of those show net them a 100 million beri increase for a total bump up of 200 million.
Luffy: 4,056,000,000 Beri
Luffy is already a billion beri man, but fighting Big Mom and defeating the world's strongest creature Kaido, whenever it happens, should send his bounty into the stratosphere. Kaido himself has a bounty of 4.6 billion, but it's unlikely that Luffy will be able to surpass that number, as he did have plenty of help in the battle and was knocked out multiple times. Of course, these details could become skewed by Big News Morgans, and the paper could lie about it being a one-vs-one, which would definitely add more to his bounty.
However, the real x-factor in Luffy's bounty increase will be whether or not the World Government finds out that Luffy has awakened his fruit. They already tried to assassinate him to prevent this from happening, but as of right now, the final CP0 agent on Onigashima has yet to report that the attempt failed. If and when they find out, it's possible that Luffy will become the most wanted man alive, surpassing even his father. The lowest Luffy's bounty would be by Wano's end is four billion.
Zoro: 1,340,000,000 Beri
Zoro has beaten many opponents on Wano, and he even left a scar on Kaido during his fight on the rooftop, but the defining moment of the arc for him was beating King. When Luffy defeated Katakuri, Big Mom's right-hand man, on Whole Cake Island, his bounty increased by one billion. Although it's possible that some of that increase came from defeating Cracker, Katakuri was the second in command of an Emperor of the Sea. Now that Zoro has defeated Kaido's right hand, it's likely that his bounty will go up a similar amount -- or maybe just a little more to put him back over a certain chef.
Nami: 266,000,000 Beri
Nami's biggest contribution to the raid so far has been taking down Ulti. Although Big Mom did most of the damage, Nami dealt the final blow, and that's usually what matters when it comes to bounty increases. On top of the 200 million, she will get an extra 50 million beri increase for beating a member of the Tobbi Roppo.
Usopp: 400,000,000 Beri
Usopp hasn't had a significant event during the raid on Onigshima that would merit a huge bounty increase. Unless something changes, he would likely get a base increase just for being a Straw Hat.
Sanji: 1,330,000,000 Beri
Like Zoro, Sanji defeated an All-Star of the Beast Pirates. Queen was another billion beri man, so this will likely notch the chef a billion beri bonus. However, he's likely to end up back below Zoro's bounty, if only to continue the gag of their continuous competition of who is stronger.
Chopper: 200 Beri
As much as Chopper deserves to be given a real bounty for once, it's hard to see Oda not continuing the trend of lowballing the poor reindeer. He has always increased by 50 beri each time, but two Emperors are going to fall, so his bounty could double... not that this will help cheer him up after he sees the number.
Robin: 630,000,000 Beri
Behind Luffy, Robin might be the most dangerous person to the World Government. The efforts of both CP0 and the Big Mom/Beast Pirate Alliance to capture her have clearly proven her value. All this, plus the fact that she defeated a member of the Tobi Roppo, means her bounty is likely to skyrocket, this time by 500 million.
Franky: 344,000,000 Beri
Franky was another Straw Hat who took down a Tobi Roppo member. This will give him a 250 million beri increase which, unfortunately for him, still puts him below God Usopp. The real question, however, is whether Franky gets a new picture or if General Franky remains on the wanted poster.
Brook: 283,000,000 Beri
The Straw Hats' musician has not played a major part in the raid. He was with Robin when she defeated Black Maria, but he left the fight to her while he cleared out the minions. He deserved a bounty increase after his stellar performance in the "Whole Cake Island" arc, but a 200 million beri increase is certain to make his eyes light up (even though he doesn't have any).
Jinbei: 688,000,000 Beri
The newest Straw Hat got to Wano late, but he has certainly done his fair share by defeating Who's-Who and helping put out the fire in the castle. This should net him a solid 250 million beri increase.
With One Piece entering its endgame, these bounty increases are likely to be some of the last in the series. The Straw Hats only have a few more chances to stir up trouble before they reach Laugh Tale and turn the world upside down.