What was Daz Bones' bounty when he was defeated by Zoro ? Around the 50 millions I'd wager considering where he was sent in Impel Down, right ? I apply the same logic here, in that the non-captain SH rarely, if ever, get a bounty higher than their opponent's.
Of course, it's kind of skewed since they haven't fought with pirates with bounties on their head. But I just don't see Oda already breaking the billion barrier with them. I mean, the Calamities got decades being just that, they have history, it's just a tad too early for me to see Zoro and Sanji breaking that Billion barrier.
After Elbaf ? Fuck yeah, even if all they do is cheer Usopp as he gets a real brave warrior of the sea. But right now, i fell it's too early, as late in the game as we are in the manga XD !