Could he go all Iblocka and hit the 3-4 block range? Probably. But that would take him out of position to box out and/or compete for rebounds. Ibaka seems to have normalized in that 7-8 rebound range and I feel like that has a lot to do with him constantly trying to contest shots.
If you remember last year, a lot of people criticized Bis' lack of high rebounding numbers. But I feel like a lot of that has to do with him trying to cover for his teammates by moving around the paint and not being able to focus on his area on the floor.
If Mully (or whoever Bis plays with) exhibits some defensive ability then Bis should see some more freedom to crash the boards, but if he's still playing next to a sieve then I wouldn't be surprised to see him stay around the 7-8ish level he's at right now.