There’s a chance that because Luffy and Blackbeard will obviously get big raises, then that will mean Oda will start inflating the bounties again and we’ll look back at Marco’s bounty and laugh hysterically, because Beckman and Shiryu have a cool 3.4 and 3.7 billion to their name and even Yassop is sitting above current Blackbeard on 2.8.
But I very much hope Oda doesn’t do this, bounties have never been perfect, but they do sort of work. If you stop to really think about it there’s a collapse (Robin is worthless, why are pre-skip Luffy and Fisher Tiger so low when they humiliated the World Gov, has nobody asked Smoker what exactly Chopper can do, why do the two legendary Giant captains who terrorised the world have a bounty lower than Bobbin) but I’m willing to put that down to the escalation as the series has gotten longer.
So I think Beckman will be just below Luffy, 1.4ish, at the most just above, and this fifth emperor, 1.5 billion bounty, will be respected. A few pirates will get above it- mostly the EoS Zoro counterparts (Mihawk, Ray, Oden, EoS Shiryu), Kuzan, EoS Sabo, Kid and Law.
And getting over current Blackbeard will be even rarer.