With Magellan and Hannyabal becoming more and more sympathetic characters I think somehow Luffy will have to win them over before escaing ID, possibly by aiding them after he sees BB OHKO Magellan.
I kinda envision Magellan about to chase after Luffy and being stopped by a blackening hand on his shoulder from behind, cut to Magellan KO'd and foaming or something. This might reveal more of the nature of BB's power to Luffy as well. The specifics don't really matter, but I don't feel like Luffy and Magellan will match up again, but that Magellan will be dishonorably defeated by a real villain and earn Luffy's empathy. Poison-ossan is just doing his job, and after Hannyabal's moving speech, Luffy will have to do something to vindicate his cause, at least partially, in the eyes of those who value upholding justice, and us, the readers.
Oda is not going to make Luffy morph into a purely selfish anti-hero, he is very heroic in his own right. Also Chief and Vice-Warden are nowhere near as despicable as they might've first seemed, and are probably more aligned with Luffy's ethos than we think. (Hannyabal even has a dream!)
So…...
Hannyabal for nakama?