Storywise would make sense to be even 2b, but seems that will be less than 1b, quite nonsense for someone that has been with WB for the last 30y, probably half of this time as his right hand man, has one of the most op fruits and has become the leader of the WB Pirates after WB death, to have a bounty lower than Jack, who couldnt do nothing close to what the main WB commanders have done in the Marineford War, or do what Marco was doing with King and Queen.
Something like 1.9b would make sense with Teach bounty, with he getting his bounty to increase to over 2b for defeating Marco in the payback war.