I think this is a face saving measure by Nitish... Sushil had told that he was in contact with many MLAs from JDU.
Maybe, it was those MLA which forced him to resign or see en masse exodus of its MLAs to BJP.
Indeed it's face saving measure.
Tomorrow Nitish will get re elected as leader of legislative party ..and will be made CM again ...
That's what it seems ...
This is a well calculated move by Nitish.
They are too shameless to resign ...and their coterie won't allow them to do that even if they tried to do for sake of show .
Remember how shamelessly this Rahul G was smiling while accepting his responsibility ...either he is retard ( which is more likely ) or he is shameless and does not care that Congress has received drubbing .