Ok, my prediction is based on this:
So "93".
Since 3.093b is out of the question as I see it, I thin 3.93B or even 4.093B might be it. Especially after Akainu got 5 billions, I really don't see any problems for Aokiji being near to four or even above four as a subordinate, which would absolutely mind-blowing since the 4B level as of now was reserved only for captains, with crews and all.
It could be even more if Oda really wants to push Kuzan near Sakazuki.