I don't think Luffy will reach the level of Roger bounty until after finding One Piece.
So in the mean time need a respectable medium where he's close to Shanks so if they meet they can be on the same level.
Zoro and Sanji is based on I can't see them catching up to Luffys bounty that much like some are suggesting. Zoro might make it to 1.5 bil and Sanji 1.3 bil.
Robin is based off her knowledge more and more people are pursuing her now.
Franky well... Sasaki was fodder in the end.
well look at it from this perspective
the world government wouldnt think luffy taking down kaido was much of a group effort .
Luffy awakened the fruit they had to change the name of , the same one joyboy had
and then went on to take down kaido after he was supposed to have been killed.
I at least see him getting over 4 billion
sanji and zoro take a step above king and queen
so perhaps sanji at 1.4 and zoro at the 1.5 mark
sasaki is worth around 500 mil , franky deserves around there too. They havent given robin a bounty that high all this while, I dont think it will escalate that much now.