Without protection, Meteor City will be taken over by Gyro.
Gon will deal with this plotline.
If Gon "saves" Meteor City from Gyro, then there has to be a Spider -- either in all or part of its current members -- to return to Meteor City and acknowledge Gon's actions.
I think Chrollo and Hisoka will be gradually postponed for different reasons.
I expect Chrollo to get wrapped up in the Succession Arc alongside Kurapika, while Hisoka will meet his end in the DC, at the hands of a single uberpowerful individual, way beyond Chrollo's level, so as to satisfy Hisoka fully in his last moments.